COVID raises risk of long-term brain injury, large U.S. study finds

Authors: Julie Steenhuysen September 22, 2022 Yahoo News

People who had COVID-19 are at higher risk for a host of brain injuries a year later compared with people who were never infected by the coronavirus, a finding that could affect millions of Americans, U.S. researchers reported on Thursday.

The year-long study, published in Nature Medicine, assessed brain health across 44 different disorders using medical records without patient identifiers from millions of U.S. veterans.

Brain and other neurological disorders occurred in 7% more of those who had been infected with COVID compared with a similar group of veterans who had never been infected. That translates into roughly 6.6 million Americans who had brain impairments linked with their COVID infections, the team said.

“The results show the devastating long-term effects of COVID-19,” senior author Dr. Ziyad Al-Aly of Washington University School of Medicine said in a statement.

Al-Aly and colleagues at Washington University School of Medicine and the Veterans Affairs St. Louis Health Care System studied medical records from 154,000 U.S. veterans who had tested positive for COVID from March 1, 2020 to Jan. 15, 2021.

They compared these with records from 5.6 million patients who did not have COVID during the same time frame, and another group of 5.8 million people from the period just before the coronavirus arrived in the United States.

Al-Aly said prior studies looked at a narrower group of disorders, and were focused largely on hospitalized patients, whereas his study included both hospitalized and non-hospitalized patients.

Memory impairments, commonly referred to as brain fog, were the most common symptom. Compared with the control groups, people infected with COVID had a 77% higher risk of developing memory problems.

People infected with the virus also were 50% more likely to have an ischemic stroke, which is caused by blood clots, compared with the never infected group.

Those who had COVID were 80% more likely to have seizures, 43% more likely to have mental health issues, such as anxiety or depression, 35% more likely to have headaches and 42% more likely to suffer movement disorders, such as tremors, compared with the control groups.

Researchers said governments and health systems must devise plans for a post-COVID world.

“Given the colossal scale of the pandemic, meeting these challenges requires urgent and coordinated – but, so far, absent – global, national and regional response strategies,”

High cholesterol, overweight and reduced physical stamina are long COVID sequelae in young adults

Authors: University of Zurich Summary: 6, 2022:Science Daily

As the Covid-19 pandemic evolves, the issue of post-infection consequences is growing in significance. Does Long Covid impact previously healthy young adults? Although this group is of great societal importance, representing the next generation and the backbone of the workforce, the intermediate-term and long-term effects of SARS-CoV-2 infections have scarcely been researched in this population. Available original research tends to focus on sufferers who were hospitalized, the elderly or those with multiple morbidities, or restricts evaluations to a single organ system.

Long Covid implications in young Swiss military personnel

A new study, funded by the Swiss Armed Forces, and conducted under the leadership of Patricia Schlagenhauf, Professor at the Epidemiology, Biostatistics and Prevention Institute of the University of Zurich (UZH), has now evaluated possible Long Covid implications in young Swiss military personnel. The study, published in the journal Lancet Infectious Diseases, was done between May and November 2021 with 29 female and 464 male participants with a median age of 21. 177 participants had confirmed Covid-19 more than 180 days prior to the testing day, and the control group was made up of 251 SARS-CoV-2 serologically negative individuals. Unlike other studies the novel test battery also evaluated cardiovascular, pulmonary, neurological, ophthalmological, male fertility, psychological and general systems.

Despite overall recovery also sequelae after recent infections remain

The findings show that young, previously healthy, non-hospitalized individuals largely recover from mild infection and that the impact of the SARS-CoV-2 virus on several systems of the body is less than that seen in older, multi-morbid or hospitalized patients. However, the study also provided evidence that recent infections — even mild ones — can lead to symptoms such as fatigue, reduced sense of smell and psychological problems for up to 180 days, as well as having a short-term negative impact on male fertility. For non-recent infections — more than 180 days back — these effects were no longer significant.

Specific constellation carries risk of developing metabolic disorders

For those with non-recent infections, however, the study — which had a long follow-up — provided evidence of a potentially risky constellation: “Increased BMI, high cholesterol and lower physical stamina is suggestive of a higher risk of developing metabolic disorders and possible cardiovascular complications,” says principal investigator Patricia Schlagenhauf. “These results have societal and public-health effects and can be used to guide strategies for broad interdisciplinary evaluation of Covid-19 sequelae, their management, curative treatments, and provision of support in young adult populations.”

Significant landmark study points the way

The study, conducted in collaboration with clinics at the University Hospital Zurich and Spiez Laboratory, is novel in that it quantitatively evaluated multi-organ function using a sensitive, minimally invasive test battery in a homogenous group of people several months after a Covid-19 infection. A valuable facet of the study was the control group, serologically confirmed to have had no SARS-CoV-2 exposure. “This combination of a unique test battery, a homogenous cohort and a control group make this a very powerful, landmark study in the evidence base on Long Covid in young adults,” says Schlagenhauf.

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Materials provided by University of ZurichNote: Content may be edited for style and length.

Journal Reference:

  1. Jeremy Werner Deuel, Elisa Lauria, Thibault Lovey, Sandrine Zweifel, Mara Isabella Meier, Roland Züst, Nejla Gültekin, Andreas Stettbacher, Patricia Schlagenhauf. Persistence, prevalence, and polymorphism of sequelae after COVID-19 in unvaccinated, young adults of the Swiss Armed Forces: a longitudinal, cohort study (LoCoMo)The Lancet Infectious Diseases, 2022; DOI: 10.1016/S1473-3099(22)00449-2

COVID-19 vaccine may not stop long term effects on older adults

Authors: Associated Press

New U.S. research on long COVID-19 provides fresh evidence that it can happen even after breakthrough infections in vaccinated people, and that older adults face higher risks for the long-term effects.

In a study of veterans published Wednesday, about one-third who had breakthrough infections showed signs of long COVID.

A separate report from the Centers for Disease Control and Prevention found that up to a year after an initial coronavirus infection, 1 in 4 adults aged 65 and older had at least one potential long COVID health problem, compared with 1 in 5 younger adults.

Long COVID refers to any of more than two dozens symptoms that linger, recur or first appear at least one month after a coronavirus infection. These can affect all parts of the body and may include fatigue, shortness of breath, brain fog and blood clots.

Coronavirus vaccines that help prevent initial infections and serious illnesses provide some protection against long COVID but mounting research shows not as much as scientists had first hoped.

The veterans study published in Nature Medicine reviewed medical records of mostly white male veterans, aged 60, on average. Of the 13 million veterans, almost 3 million had been vaccinated last year, through October.

About 1%, or nearly 34,000, developed breakthrough infections. Lead author Dr. Ziyad Al-Aly noted that the study was done before the highly contagious omicron variant appeared at the end of the year and said the rate of breakthrough infections has likely increased.

Breakthrough infections and long COVID symptoms were more common among those who had received Johnson & Johnson’s single-dose shot compared with two doses of either Moderna or Pfizer vaccines. Whether any had received booster shots is not known; the first booster wasn’t OK’d in the U.S. until late September.

Overall, 32% had long COVID symptoms up to six months after breakthrough infections. That’s compared with 36% of unvaccinated veterans who had been infected and developed long COVID.

Vaccination reduced the chances for any long COVID symptoms by a “modest” 15%,” although it cut the risk in half for lingering respiratory or clotting problems, said Al-Aly, a researcher with Washington University and the Veterans Affairs health system in St. Louis. These symptoms included persistent shortness of breath or cough and blood clots in lungs or veins in the legs.

Patients who have taken Johnson & Johnson’s COVID-19 vaccine have tested positive for virus more often than their Moderna and Pfizer counterparts.FREDERIC J. BROWN/AFP via Getty Images

Infectious disease expert Dr. Kristin Englund, who runs a center for long COVID patients at the Cleveland Clinic, said the Nature Medicine study mirrors what she sees at her clinic. Long COVID patients there include people who were vaccinated and received boosters.

“As we have no clear treatments for long COVID, it is important for everyone to get vaccinated and use other proven methods of prevention such as masking and social distancing in order to prevent infections with COVID and thus long COVID,” Englund said.

The CDC report, released Tuesday, used medical records for almost 2 million U.S. adults from the start of the pandemic in March 2020 to last November. They included 353,000 who had COVID-19. Patients were tracked for up to a year to determine if they developed any of 26 health conditions that have been attributed to long COVID.

Those who had COVID were much more likely than other adults without COVID to develop at least one of these conditions, and risks were greatest for those aged 65 and older. Information on vaccination, sex and race was not included.

Breathing problems and muscle aches were among the most common conditions.

Older adults’ risks were higher for certain conditions, including strokes, brain fog, kidney failure and mental health problems. The findings are worrisome because those conditions can hasten older adults’ needs for long-term care, the report authors said.

They stressed that routine assessment of all COVID patients “is critical to reduce the incidence” of long COVID.

Long COVID after breakthrough SARS-CoV-2 infection

Authors: Ziyad Al-AlyBenjamin Bowe & Yan Xie 

Nature Medicine volume 28, pages1461–1467 (2022)


The post-acute sequelae of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection—also referred to as Long COVID—have been described, but whether breakthrough SARS-CoV-2 infection (BTI) in vaccinated people results in post-acute sequelae is not clear. In this study, we used the US Department of Veterans Affairs national healthcare databases to build a cohort of 33,940 individuals with BTI and several controls of people without evidence of SARS-CoV-2 infection, including contemporary (n = 4,983,491), historical (n = 5,785,273) and vaccinated (n = 2,566,369) controls. At 6 months after infection, we show that, beyond the first 30 days of illness, compared to contemporary controls, people with BTI exhibited a higher risk of death (hazard ratio (HR) = 1.75, 95% confidence interval (CI): 1.59, 1.93) and incident post-acute sequelae (HR = 1.50, 95% CI: 1.46, 1.54), including cardiovascular, coagulation and hematologic, gastrointestinal, kidney, mental health, metabolic, musculoskeletal and neurologic disorders. The results were consistent in comparisons versus the historical and vaccinated controls. Compared to people with SARS-CoV-2 infection who were not previously vaccinated (n = 113,474), people with BTI exhibited lower risks of death (HR = 0.66, 95% CI: 0.58, 0.74) and incident post-acute sequelae (HR = 0.85, 95% CI: 0.82, 0.89). Altogether, the findings suggest that vaccination before infection confers only partial protection in the post-acute phase of the disease; hence, reliance on it as a sole mitigation strategy may not optimally reduce long-term health consequences of SARS-CoV-2 infection. The findings emphasize the need for continued optimization of strategies for primary prevention of BTI and will guide development of post-acute care pathways for people with BTI.


The post-acute sequelae of SARS-CoV-2 infection—also referred to as Long COVID—have been characterized1. Increasingly, vaccinated individuals are being diagnosed with COVID-19 as a result of breakthrough SARS-CoV-2 infection (BTI)2,3. Whether people with BTI experience post-acute sequelae is not clear. Addressing this knowledge gap is important to guide public health policy and post-acute COVID-19 care strategies.

Here we leverage the breadth and depth of the electronic healthcare databases of the US Department of Veterans Affairs to address the question of whether people with BTI develop post-acute sequelae. We characterize the risks and 6-month burdens of a panel of prespecified outcomes in a cohort of people who experienced BTI after completion of vaccination in the overall cohort and by care setting of the acute phase of the disease (that is, whether people were not hospitalized, hospitalized or admitted to an intensive care unit (ICU) during the first 30 days after a positive test). We then undertake a comparative evaluation of the magnitude of risk in people with BTI versus those with SARS-CoV-2 infection and no prior vaccination and, separately, hospitalized people with BTI versus those hospitalized with seasonal influenza.


Post-acute sequelae in BTI versus controls without SARS-CoV-2 infection

There were 33,940 and 4,983,491 participants in the BTI group and a contemporary control group of users of the Veterans Health Administration from 1 January 2021 to 31 October 2021 with no record of a positive SARS-CoV-2 test, respectively. BTI participants had a positive SARS-CoV-2 test with prior record of a complete vaccination defined following Centers for Disease Control and Prevention (CDC) guidelines at 14 days after first Janssen (Johnson & Johnson)(Ad26.COV2.S) vaccination and 14 days after second Pfizer-BioNTech (BNT162b2) or Moderna (mRNA-1273) vaccination. The demographic and health characteristics of the BTI and the control groups before and after weighting are presented in Supplementary Tables 14. During the enrollment period, the overall rate of BTI within those fully vaccinated was 10.60 (95% CI: 10.52, 10.70) per 1,000 persons at 6 months; rates of breakthrough by vaccine type are presented in Supplementary Data Table 1.

For all analyses, we provide two measures of risk: (1) we estimated the adjusted HRs of a set of incident prespecified outcomes in people with BTI versus the control group; and (2) we estimated the adjusted excess burden of each outcome due to BTI per 1,000 persons 6 months after a positive SARS-CoV-2 test on the basis of the difference between the estimated incidence rate in individuals with BTI and the control group. Assessment of standardized mean differences of participant characteristics (from data domains including diagnoses, medications and laboratory test results) after application of weighting showed that they are well-balanced in each analysis of incident outcomes (Supplementary Fig. 1).

Compared to the contemporary control group, people who survived the first 30 days of BTI exhibited an increased risk of death (HR = 1.75, 95% CI: 1.59, 1.93) and excess burden of death estimated at 13.36 (95% CI: 11.36, 15.55) per 1,000 persons with BTI at 6 months; all burden estimates represent excess burden and are given per 1,000 persons with BTI at 6 months (Fig. 1). People with BTI also had an increased risk of having at least one post-acute sequela of SARS-CoV-2 (PASC) (HR = 1.50, 95% CI: 1.46, 1.54; burden of 122.22, 95% CI: 115.31, 129.24) (Supplementary Table 5).

figure 1
Fig. 1: Risk and 6-month excess burden of post-acute sequelae in people with BTI compared to the contemporary control group.

Compared to the control group, 30-day survivors of BTI exhibited increased risk of post-acute sequelae in the pulmonary (HR = 2.48 (2.33, 2.64); burden of 39.82 (36.83, 42.99)) and several extrapulmonary organ systems, including cardiovascular disorders (HR = 1.74 (1.66, 1.83); burden of 43.94 (39.72, 48.35)), coagulation and hematologic disorders (HR = 2.43 (2.18, 2.71); burden of 13.66 (11.95, 15.56)), fatigue (HR = 2.00 (1.82, 2.21); burden of 15.47 (13.21, 17.96)), gastrointestinal disorders (HR = 1.63 (1.54, 1.72); burden of 37.68 (33.76, 41.80)), kidney disorders (HR = 1.62 (1.47, 1.77); burden of 16.12 (13.72, 18.74)), mental health disorders (HR = 1.46 (1.39, 1.53); burden of 45.85 (40.97, 50.92)), metabolic disorders (HR = 1.46 (1.37, 1.56); burden of 30.70 (26.65, 35.00)), musculoskeletal disorders (HR = 1.53 (1.42, 1.64); burden of 19.81 (16.56, 23.31)) and neurologic disorders (HR = 1.69 (1.52, 1.88); burden of 11.60 (9.43, 14.01)). Risk and excess burden of each individual sequela and by organ system are provided in Extended Data Fig. 1 (Supplementary Table 6) and Fig. 1 (Supplementary Table 5), respectively.

The results were consistent in analyses considering a historical control group (n = 5,785,273) as the referent category (Extended Data Fig. 2 and Supplementary Table 7) and, separately, people who were vaccinated for SARS-CoV-2 and did not experience a BTI (n = 2,566,369) as another alternative control group (Extended Data Fig. 3 and Supplementary Table 8).

The risk of death was increased in the 30–90 days and also increased, but to a lesser extent, in the 90–180 days after a positive SARS-CoV-2 test (Supplementary Table 9). The risk of incident sequelae was increased in the 30–90 days after a positive SARS-CoV-2 test. In the period between 90 days and 180 days after testing positive, there was increased risk of both incident sequalae—albeit in lesser magnitude than the risk in days 30–90—and increased risk of recurrent or persistent sequalae (Supplementary Table 9).

Compared to the contemporary control group, there was increased risk of death, at least one PASC and organ involvement in people who were not immunocompromised before BTI (Extended Data Fig. 4a and Supplementary Table 10); the risks were generally higher in those who were immunocompromised before BTI (Extended Data Fig. 4a and Supplementary Table 10). Analyses of people with BTI showed that the risks of death, at least one PASC and organ system involvement were consistently higher in people who were immunocompromised versus those who were not before BTI (Extended Data Fig. 4b and Supplementary Table 10).

Of people with BTI, analyses by vaccine type suggested that there is no statistically significant difference in risk of post-acute death among the three SARS-CoV-2 vaccines (Pfizer-BioNTech (BNT162b2), Moderna (mRNA-1273) and Janssen (Johnson & Johnson) (Ad26.COV2.S)). Both BNT162b2 and mRNA-1273 were associated with decreased risk of at least one PASC: pulmonary and extrapulmonary organ involvement. There was no statistically significant difference in risk of any of these outcomes between BNT162b2 and mRNA-1273 (Supplementary Table 11).

Post-acute sequelae in BTI by care setting of the acute phase of the disease

The demographic and health characteristics of people with BTI who were not hospitalized, who were hospitalized and who were admitted to ICU during the acute phase of the disease before and after weighting are provided in Supplementary Tables 12 and 13. Evaluation of standardized mean differences of baseline participant characteristics after the application of the weighting suggested good balance (Supplementary Fig. 2).

Compared to the control group of people without evidence of SARS-CoV-2 infection, people who were not hospitalized during the first 30 days of BTI exhibited an increased risk of death (HR = 1.29 (1.12, 1.49); burden of 7.77 (5.62, 10.24)); the risk was further increased in those who were hospitalized (HR = 2.69 (2.33, 3.12); burden of 24.79 (20.39, 29.86)) and was highest in those who were admitted to ICU (HR = 5.68 (4.55, 7.09); burden of 60.02 (46.85, 76.19)). The risk of having at least one post-acute sequela was evident in non-hospitalized people (HR = 1.25 (1.20, 1.30); burden of 77.60 (68.40, 87.04)), was further increased in those who were hospitalized (HR = 2.95 (2.80, 3.10); burden of 334.10 (315.90, 352.53)) and was highest in those admitted to ICU (HR = 3.75 (3.38, 4.16); burden of 421.39 (383.37, 459.56)) (Fig. 2 and Supplementary Table 14).

figure 2
Fig. 2: Risk and 6-month excess burden of post-acute sequelae in those with BTI by acute phase care setting.

People who were not hospitalized exhibited small but significant increased risk of post-acute sequelae, including cardiovascular, coagulation and hematologic, gastrointestinal, mental health, metabolic, musculoskeletal and pulmonary disoders, as well as increased risk of fatigue (Fig. 2 and Supplementary Table 14). The risks were further increased in people who were hospitalized (Fig. 2 and Supplementary Table 14) and highest in those admitted to the ICU (Fig. 2 and Supplementary Table 14). Analyses of individual sequela are presented in Extended Data Fig. 5 and Supplementary Table 15.

Post-acute sequelae in BTI versus SARS-CoV-2 infection without prior vaccination

To place the magnitude of risk of post-acute sequelae in people with BTI in broad context of post-acute COVID-19 manifestations, we developed a comparative approach to evaluate the risk of organ system involvement in people with BTI (n = 33,940) versus people with SARS-CoV-2 infection and no prior history of vaccination (n = 113,474) (Supplementary Tables 1 and 16). Assessment of standardized mean differences of baseline characteristics in the weighted cohorts suggested good balance (Supplementary Figs. 3 and 4 and Supplementary Tables 4 and 17).

People with BTI exhibited lower risk of death (HR = 0.66 (0.58, 0.74); burden of −10.99 (−13.45, −8.22); negative values denote reduced burden in BTI relative to SARS-CoV-2 infection) and lower risk of post-acute sequelae (HR = 0.85 (0.82, 0.89); burden of −43.38 (−53.22, −33.31)) compared to those with SARS-CoV-2 infection and no prior history of vaccination (Fig. 3 and Supplementary Table 18). Comparatively, the risk of post-acute sequelae in all the examined organ systems was lower in people with BTI versus those with SARS-CoV-2 infection without prior vaccination. BTI was associated with lower risk of 24 of the 47 sequelae examined compared to those with SARS-CoV-2 infection without prior vaccination (Extended Data Fig. 6 and Supplementary Table 19). The reduced risk was evident (albeit weak) in those who were immunocompromised and in those who were not immunocompromised (Supplementary Table 20).

figure 3
Fig. 3: Risk and 6-month excess burden of post-acute sequelae in people with BTI compared to those with SARS-CoV-2 infection without prior vaccination.

Analyses within each care setting suggested that the risk reduction in BTI versus SARS-CoV-2 infection on both the relative (HR) and absolute (burden) scale generally becomes increasingly more pronounced as the acuity of the care setting increased (from non-hospitalized to admitted to ICU) (Fig. 4 and Supplementary Table 21). BTI was associated with less risk of death and at least one PASC in all care settings. There was also a consistently reduced risk of hematologic and coagulation disorders and pulmonary disorders in BTI versus SARS-CoV-2 infection without prior vaccination across all care settings.

figure 4
Fig. 4: Risk and 6-month excess burden of post-acute sequelae in those with BTI compared to those with SARS-CoV-2 infection without prior vaccination by acute phase care setting.

Post-acute sequelae in people hospitalized with BTI versus seasonal influenza

We developed a comparative analysis to better understand how people hospitalized with BTI (n = 3,667) fare relative to those who are hospitalized with seasonal influenza (n = 14,337). Demographic and health characteristics before and after weighting are provided in Supplementary Tables 22 and 23. Examination of standardized mean differences of baseline characteristics after application of overlap weighting demonstrated good balance (Supplementary Fig. 5).

Compared to people who were hospitalized with seasonal influenza, people with BTI who were hospitalized during the acute phase of the disease and survived the first 30 days exhibited an increased risk of death (HR = 2.43 (2.02, 2.93); burden of 43.58 (31.21, 58.26)) and increased risk of having at least one post-acute sequela (HR = 1.27 (1.19, 1.36); burden of 87.59 (63.83, 111.40)) (Extended Data Fig. 7 and Supplementary Table 24). People with BTI exhibited increased risk of sequelae in all the examined organ systems compared to those with seasonal influenza. Results of individual sequalae are presented in Supplementary Fig. 6 and Supplementary Table 25.

Positive and negative outcome controls

To assess whether our approach reproduces established knowledge, we tested the association between SARS-CoV-2 infection without prior vaccination and the risk of fatigue (a cardinal post-acute sequela of COVID-19, where, based on prior evidence, we would expect a positive association). The results showed that, compared to the contemporary control group, people with SARS-CoV-2 infection and without prior vaccination exhibited increased risk of fatigue (HR = 2.79 (2.57, 303)) (Extended Data Table 1a).

To assess the putative presence of spurious associations, we tested the association between BTI and several negative outcome controls where there was no biologic plausibility or epidemiologic evidence that an association is expected. We used the same data sources, cohort building process, covariate selection approach (including predefined and algorithmically selected high-dimensional covariates), weighting method and interpretation of results. The results suggested no significant association between BTI and risk of any of the negative outcome controls (Extended Data Table 1a).

To further test the rigor of our approach, we tested as a pair of negative exposure controls receipt of influenza vaccination in odd-numbered (n = 605,453) versus even-numbered (n = 571,291) calendar days between 1 March 2020 and 15 January 2021. Examination of the associations of receipt of influenza vaccine on odd-numbered versus even-numbered calendar days and each outcome yielded non-significant results, consistent with our a priori expectations for a successful application of negative exposure controls (Extended Data Table 1b).


In this study of 33,940 people with BTI, 4,983,491 in the contemporary control, 5,785,273 in the historical control, 2,566,369 in the vaccinated control, 113,474 in the SARS-CoV-2 infection without prior vaccination group and 14,337 in the seasonal influenza group, we show that, compared to non-infected controls, people who survive the first 30 days of BTI exhibited increased risk of death and post-acute sequelae in the pulmonary and several extrapulmonary organ systems. The risks of death and post-acute sequelae were evident among non-hospitalized people, further increased among hospitalized people and highest among people who were admitted to ICU during the acute phase of the disease. Our comparative approach shows that risks of death and post-acute sequelae were lower in people with BTI versus people with SARS-CoV-2 infection without prior vaccination. Analyses of BTI versus SARS-CoV-2 infection without prior vaccination within the same care setting showed that this risk reduction was progressively more evident as care acuity of the acute phase of the disease increased from non-hospitalized to hospitalized and admitted to ICU and was consistently most pronounced for coagulation and pulmonary disorders. In comparative analyses among people who were hospitalized during the acute phase of the disease, those with BTI exhibited higher risks of death and post-acute sequelae than those with seasonal influenza. The constellation of findings shows that the burden of death and disease experienced by people with BTI is not trivial. Our comparative analyses provide a framework to better evaluate and contextually understand risks of the post-viral condition in people with BTI versus non-infected controls, versus SARS-CoV-2 infection without prior vaccination and versus seasonal influenza. The findings show that vaccination only partially reduces the risk of death and post-acute sequelae, suggesting that reliance on it as a sole mitigation strategy may not most optimally reduce the risk of the long-term health consequences of SARS-CoV-2 infection. Our results emphasize the need for continued optimization of primary prevention strategies of BTIs and will inform post-acute care approaches for people with BTI.

We examined the risk of death and post-acute sequelae in those with BTI versus several controls of people without evidence of SARS-CoV-2 infection, including (1) a contemporary control of people exposed to the same broader forces of the pandemic (lockdowns and economic, social and environmental stressors); (2) a historical control from a pre-pandemic era that represents a baseline unaffected by the disruptions of the pandemic; and (3) a vaccinated control group. The results show two key findings: (1) Long COVID, including increased risks of death and myriad post-acute sequelae in the pulmonary and extrapulmonary organ systems, also manifests in vaccinated individuals who experience a BTI; and (2) the range of post-acute sequelae in various organ systems in BTI does not appear to be different than COVID-19 without prior vaccination1,4,5,6,7,8,9,10,11,12. Our analyses of BTI versus SARS-CoV-2 infection without prior vaccination show that, comparatively, the magnitude of the risks of death and post-acute sequelae was lower in people with BTI versus those with SARS-CoV-2 infection who had not been previously vaccinated for it. These results show that, although vaccination may partially reduce the risks of post-acute death and disease, to most optimally reduce this burden requires continued emphasis on primary prevention of breakthrough SARS-CoV-2 infection as a goal of public health policy.

Although the absolute rates are smaller than in those with SARS-CoV-2 infection without prior vaccination, given the scale of the pandemic and the potential for breakthrough cases to continue to accumulate, the overall burden of death and disease after BTI will likely be substantial, will further add to the toll of this pandemic and will represent an additional strain on already overwhelmed health systems. In planning and development of health resources, governments and health systems should take into account the care needs of people with post-acute sequelae after BTI13.

Our analyses suggest that this risk reduction (of post-acute sequelae) was most pronounced in recipients of BNT162b2 and mRNA-1273 vaccines (compared to Ad26.COV2.S). Although these results recapitulate evidence of vaccine effectiveness in the acute phase of COVID-19, the mechanism or mechanisms underlying this carry-through effect of risk reduction from the acute to the post-acute phase of the disease is not entirely clear. One putative interpretation of these results is that vaccine-induced reduction in severity of the acute infection may then translate into less long-term risk of post-acute health outcomes. In other analyses, we also show that the reduced risk of post-acute sequelae in people with BTIs was partially eroded in people with immunocompromised status, suggesting a putative immune-related mechanism in the expression of post-acute sequelae that may be influenced by vaccination.

We also show that the risk of post-acute sequelae is higher in people with BTI than in people with seasonal influenza—a well-characterized respiratory viral illness. This extends previous evidence showing that the risk of post-acute sequelae in people with SARS-CoV-2 infection was higher than those with seasonal influenza and again emphasizes the importance of prevention of both SARS-CoV-2 infection and BTI1.

This study has several strengths. To our knowledge, it is the first large study to characterize the risks of post-acute sequelae of BTI at 6 months. We leveraged the vast national healthcare databases of the US Department of Veterans Affairs (the largest nationally integrated healthcare delivery system in the United States) to characterize the risk and 6-month burden of a comprehensive set of prespecified incident health outcomes in patients who survived the first 30 days of BTI versus several control groups (contemporary, historical and vaccinated controls). In addition to evaluating risk of BTI versus those with no evidence of SARS-CoV-2 infection in the overall cohort and by care setting of the acute phase of the disease (non-hospitalized, hospitalized and admitted to ICU), we also undertook a comparative evaluation of BTI versus SARS-CoV-2 infection in people who had not been previously vaccinated and, separately, BTI versus seasonal influenza. We used advanced statistical methodologies and adjusted through weighting for a battery of predefined covariates selected based on prior knowledge and algorithmically selected covariates from high-dimensional data domains, including diagnoses, prescription records and laboratory test results. We evaluated the rigor of our approach by testing positive and negative outcome controls to determine whether our approach would produce results consistent with pre-test expectations.

The study also has several limitations. The BTI and SARS-CoV-2 infection groups included only those who had a positive test for SARS-CoV-2 and did not include those who may have had an infection with SARS-CoV-2 but were not tested; however, if present, this will bias the estimates toward the null. Although the Veterans Affairs population is comprised of mostly men, it includes 8–10% women, which, across the groups in our study, included 1,300,744 female participants. Although we adjusted through the overlap weighting approach for a large battery of predefined and algorithmically selected covariates, and although our approach demonstrated good balance for more than 734 covariates (including all those that were available in the data but not included in the weighting process) from several data domains, including diagnoses, prescription medications and laboratory test results, and resulted in successful testing of positive outcome controls and negative outcome controls, we cannot completely rule out residual confounding. Our approach does not evaluate the severity of each outcome. Finally, the COVID-19 global pandemic is highly dynamic. As vaccine uptake continues to increase, as vaccine schedules continue to be optimized, as vaccine effectiveness wanes over time since vaccination, as booster vaccinations are deployed, as treatment strategies of the acute phase of COVID-19 continue to improve and as new variants of the virus emerge, it is likely that the epidemiology of BTI and its downstream sequelae may also change over time.

In sum, our findings provide evidence of increased risk of death and post-acute sequelae in people with BTI compared to controls with no evidence of SARS-CoV-2 infection; the risks were reduced in comparative analyses involving BTI versus SARS-CoV-2 infection without prior vaccination. Our results show that SARS-CoV-2 vaccination before infection only partially reduced the risk of death and post-acute sequelae. Measures for the prevention of breakthrough infections are needed to most optimally reduce the risk of the long-term health consequences of SARS-CoV-2 infection.


All participants who were eligible for this study were enrolled; no a priori sample size analyses were conducted to guide enrollment. All analyses were observational, and investigators were aware of participant exposure and outcome status. A summary of the major design elements is presented in Supplementary Table 26, and an analytic flowchart is provided in Supplementary Fig. 7.


Cohort participants were identified from the US Veterans Health Administration (VHA) electronic health databases. The VHA provides healthcare to discharged veterans of the US armed forces in a nationally integrated network of healthcare systems that includes more than 1,415 healthcare facilities. Veterans enrolled in the VHA have access to a comprehensive medical benefits package that includes outpatient services; preventive, primary and specialty care; mental health care; geriatric care; inpatient hospital care; extended long-term care; prescriptions; home healthcare; medical equipment; and prosthetics. The VHA healthcare databases are updated daily.


We first identified users of the VHA who were alive on 1 January 2021 (n = 5,430,912). Use of the VHA was defined as having record of use of outpatient or inpatient service, receipt of medication or use of laboratory service with the VHA healthcare system in the 2 years prior (Supplementary Fig. 8). Among these, 163,024 participants had a record of a first positive SARS-CoV-2 test from 1 January 2021 to 31 October 2021, and 5,140,387 had no record of any positive SARS-CoV-2 test between 1 January 2020 and 1 December 2021. Participants were followed until 1 December 2021.

To construct a group of people with BTI, we selected, from those with a positive SARS-CoV-2 test (n = 163,024), those with a record of completion of an Ad26.COV2.S, mRNA-1273 or BNT162b2 vaccination before the date of their first positive SARS-CoV-2 test (n = 34,863). Completion of vaccination was defined following CDC guidelines at the 14th day after the second shot of the mRNA-1273 or BNT162b2 vaccination series or the 14th day after the first shot of the Ad26.COV2.S vaccination. Setting the date of first positive SARS-CoV-2 test as time zero (T0), we then selected those alive 30 days after T0, resulting in a cohort of 33,940 participants in the BTI group.

We then constructed several control groups; the rationale for each of these control groups is provided in Supplementary Fig. 9. To build a contemporary control group of people with no evidence of SARS-CoV-2 infection, we then used the 5,140,387 users of the VHA who had no record of a SARS-CoV-2-positive test. Among these participants, we randomly assigned a T0 to each participant in the group on the basis of the distribution of the T0 dates in those with BTI. We finally selected those who were alive 30 days after their T0 (n = 4,983,491). The contemporary control group represents contemporaneous users of the VHA who were subject to the broader forces of the pandemic but did not contract SARS-CoV-2 infection. Of these, the 2,566,369 who had record of a SARS-CoV-2 vaccination before their T0 served as a vaccinated control group. The vaccinated control group represents contemporaneous users of the VHA who share the characteristic of being vaccinated with the breakthrough group and have a major distinction in that they did not contract SARS-CoV-2 infection subsequent to their vaccination.

To build an alternate control group during a period of time where participants were not subject to the influence of the pandemic, we identified users of the VHA who were alive on 1 January 2018 (n = 6,084,973) and who had no history of a positive SARS-CoV-2 test (n = 5,938,519). After randomly assigning a T0 in 2018 on the basis of the distribution of the calendar dates of T0 in those with BTI, 5,785,273 were alive 30 days after T0. Participants were followed until 1 December 2018. This group served as the historical control group.

To build the group of people with SARS-CoV-2 infection and without prior vaccination as a means of investigating the effect of prior vaccination on the risk of post-acute sequalae, we identified, from the 163,024 people with a first positive SARS-CoV-2 test from 1 January 2021 to 31 October 2021, 118,185 who had no record of any SARS-CoV-2 vaccination up through 30 days after first positive SARS-CoV-2 test (T0). We then selected the 113,474 who were alive 30 days after T0 to comprise the group of people with SARS-CoV-2 infection and no prior vaccination.

Finally, to compare post-acute sequelae of those hospitalized with BTI during the acute phase of the illness to those hospitalized with seasonal influenza, we separately identified 15,160 VHA users hospitalized with positive seasonal influenza test 5 days before or 30 days after the test between 1 October 2016 and 29 February 2020. We set the date of the positive seasonal influenza test as T0. To ensure no overlap with the BTI group, participants who had no record of a positive SARS-CoV-2 test were then selected (n = 14,431). From these, we selected 14,337 who were alive 30 days after their T0 to constitute the seasonal influenza group. Duration of follow-up was randomly assigned on the basis of follow-up in the BTI group.

Data sources

Data used in this study were obtained from the VHA Corporate Data Warehouse (CDW). Within CDW, the patient data domain provided information on demographic characteristics; the outpatient encounters domain and inpatient encounters domain provided information on health characteristics, including data on timing and location of interactions with the healthcare system, diagnoses and procedures; the pharmacy and barcode medication administration domains provided medication records; and the laboratory results domain provided laboratory test information in both outpatient and inpatient settings5,6. The COVID-19 Shared Data Resource provided information on SARS-CoV-2 test results and SARS-CoV-2 vaccination status. The 2019 Area Deprivation Index (ADI) at each cohort participant residential address was used as a contextual measure of socioeconomic disadvantage14.

Post-acute sequelae

We prespecified a set of outcomes based on prior evidence on the post-acute sequelae of SARS-CoV-2 infection—also referred to as Long COVID4,5,6,7,8,9,10,11,12. Outcomes were defined using validated definitions leveraging information from several data domains, including diagnoses, prescription medications and laboratory test results, at the time of first record of occurrence in the data5,6,15,16,17,18,19,20,21. Incident post-acute sequelae were examined in a cohort with no record of the health condition in the 2 years before T0. We additionally examined outcomes of death and having at least one of post-acute sequelae that was defined at the time of the first incident prespecified post-acute sequelae in each participant.

Additionally, we defined a set of outcomes where we aggregated the prespecified post-acute sequelae, where applicable, by organ system. These included cardiovascular disorders, coagulation and hematologic disorders, fatigue, gastrointestinal disorders, kidney disorders, mental health disorders, metabolic disorders, musculoskeletal disorders, neurologic disorders and pulmonary disorders. All outcomes were assessed starting from 30 days after T0.


We included a set of predefined covariates based on prior knowledge4,5,6,7,8,9,10,11,12,19,22,23,24,25,26 and algorithmically selected covariates. Predefined covariates included demographic information (age, race and sex); contextual information (ADI); measures of the intensity of healthcare interaction in the 2 years before T0, including the number of outpatient visits, the number of inpatient visits, the number of unique medications the participant received a prescription for and the number of routine blood panels that were performed; and prior history of receiving an influenza vaccination. We also included smoking status as a covariate. Health characteristics included prior history of anxiety, cancer, cardiovascular disease, cerebrovascular disease, chronic kidney disease, peripheral artery disease, dementia, depression, type 2 diabetes mellitus and chronic obstructive pulmonary disease, and measures of estimated glomerular filtration rate, systolic and diastolic blood pressure, and body mass index (BMI). We also included, as measures of spatiotemporal differences, the calendar week of enrollment and geographic region of receipt of care defined by Veterans Integrated Services Networks (VISN).

In consideration of the dynamicity of the pandemic, for analyses that compared BTI, SARS-CoV-2 infection without prior vaccination and the contemporary control, additional covariates included SARS-CoV-2 testing capacity, SARS-CoV-2 positivity rates, hospital system capacity (the total number of inpatient hospital beds) and inpatient bed occupancy rates (the percentage of hospital beds that were occupied) as well as a measure of the proportions of SARS-CoV-2 variants by Health and Human Services region26. These measures were ascertained for each participant in the week before cohort enrollment at the location of the healthcare system at which they received care. In analyses of the vaccinated control, we additionally included calendar week of first vaccination shot. All continuous covariates were treated as natural cubic splines unless heavily skewed toward zero.

In addition to the predefined covariates, we leveraged the high dimensionality of VA data where we developed and deployed a high-dimensional variable selection algorithm to identify covariates that may potentially confound the examined associations27. Using classifications from the Clinical Classifications Software Refined version 2021.1, available from the Healthcare Cost and Utilization Project sponsored by the Agency for Healthcare Research and Quality, more than 70,000 ICD-10 diagnoses codes in the year before T0 for each participant were classified into 540 diagnostic categories28,29,30. Using the VA drug classification system, 3,425 different medications were classified into 543 medication classes31,32. Finally, laboratory results from 38 different laboratory measurements were classified into 62 laboratory test abnormalities, defined by being above or below the corresponding reference ranges, on the basis of the recorded Logical Observation Identifiers Names and Codes. Of the high-dimensional variables that occurred at least 100 times in participants in each group (up to 821), we selected the top 100 variables with the highest relative risk for differences in group membership for inclusion in models.

Statistical analysis

Mean (standard deviation) and frequency (percentage) of select characteristics are reported in the BTI group, SARS-CoV-2-infected group without prior vaccination, the contemporary control group, the historical control group, the vaccinated control group and the seasonal influenza group, where appropriate. Characteristics of those with BTI by hospitalization status are additionally presented. Vaccination characteristics for those with BTI are reported as well as BTI rates per 1,000 persons at 6 months for those vaccinated from 1 January to 31 October 2021.

To balance baseline characteristics, including predefined and high-dimensional variables across comparison groups, we applied an overlap weighting approach in our analyses. In brief, logistic regressions were constructed for probability of group membership of the groups being compared, using the predefined and high-dimensional covariates as independent variables, in separate subcohorts with no prior history of the outcome being examined, estimating propensity scores of the probability of group assignment33,34. In consideration of variability in duration of potential follow-up, calendar week of enrollment was included to balance length of follow-up between cohorts (uncensored duration of follow-up was included for comparison versus seasonal influenza). Propensity scores were then used in construction of the overlap weights whose application achieved similar baseline characteristic distributions across groups while providing higher weights to those with baseline characteristics more similar to those in other groups. Weights were then applied to Cox survival models to estimate HRs, where follow-up started 30 days after the date of testing positive. Standard errors were estimated by applying the robust sandwich variance estimator method. Covariate balance among all predefined and high-dimensional variables were assessed for each model through the standardized mean difference, where a difference <0.1 was taken as evidence of balance. We estimated the incidence rate difference (referred to as excess burden) between groups per 1,000 participants at 6 months after the start of follow-up based on the difference in survival probability in the relevant groups.

We first examined the risk and excess burden of individual post-acute sequelae, post-acute sequelae by organ system, at least one post-acute sequela and death between the BTI group, those with SARS-CoV-2 infection without prior vaccination and the contemporary control. We then compared risks of the BTI group with the historical control and, separately, with the vaccinated control.

Further analyses were conducted to better understand the risk in BTI versus the contemporary control. To investigate risk of post-acute sequalae before and after 90 days of follow-up, we conducted analyses that examined risk during the first 30–90 days, and during the 90–180 days, after T0. Examination of the risk from the 90–180 days was done overall, for incident outcomes during this period (where there was no record of the outcome during the 30–90-day period) and for recurrent or persistent outcomes during this period (where there was a prior record of the outcome during the 30–90-day period). We then comparatively evaluated the risks between the BTI and contemporary control based on their immunocompromised status, where immunocompromised status was defined (according to the CDC definition) by a history of organ transplantation, advanced kidney disease (an estimated glomerular filtration rate of less than 15 ml/min/1.73 m2 or end-stage renal disease), cancer, HIV or conditions with prescriptions of more than 30-day use of corticosteroids or immunosuppressants, including systemic lupus erythematosus and rheumatoid arthritis. We lastly compared the risks and burden of death, at least one PASC, pulmonary disorders and extrapulmonary disorders within those with BTI by type of vaccination received.

We then examined the risk and excess burden associated with BTI by care setting of the acute phase of the disease. Risks were estimated for individual sequelae and risks and excess burden of organ system involvement, at least one post-acute sequela and death in those with a BTI who were not hospitalized, who were hospitalized and who were admitted to ICU during the 5 days before and 30 days after their positive SARS-CoV-2 test compared to the contemporary control group.

We additionally examined differences in risk and burden between BTI and SARS-CoV-2 infection without prior vaccination by severity of the acute phase of the disease (non-hospitalized, hospitalized and admitted to ICU).

Finally, we compared the risks and excess burden of individual post-acute sequelae, post-acute sequelae by organ system, at least one post-acute sequela and death between those hospitalized with BTI and those hospitalized with seasonal influenza.

Positive and negative controls

We examined, as positive outcome controls, the risks of fatigue in those with SARS-CoV-2 infection without prior vaccination compared to the contemporary and historical control groups as a means of testing whether our approach would reproduce established knowledge8,9,10,11,12.

The application of negative outcome control may help detect both suspected and unsuspected sources of spurious biases. We, therefore, tested comparing BTI to the contemporary and historical controls, the risk of atopic dermatitis, accidental poisoning, accidental injury, fitting of a hearing aid or contact lenses, ingrown toenail and scarring as negative outcome controls—where no prior knowledge suggests that an association is expected. Additionally, we tested a pair of negative-exposure controls; we expected that receipt of the influenza vaccine on odd-numbered (n = 605,453) versus even-numbered (n = 571,291) calendar days between 1 March 2020 and 15 January 2021 would be associated with similar risks of the outcomes examined in our analyses. The successful testing of positive outcome controls, negative outcome controls and negative exposure controls may lessen concerns about biases related to study design, covariate selection, analytic approach, outcome ascertainment, unmeasured confounding and other potential sources of latent biases35,36.

All analyses were two-sided. In all analyses, a 95% CI that excluded unity was considered evidence of statistical significance. All analyses were conducted in SAS Enterprise Guide 8.2, and all figures were generated in R version 4.0.4. This study was approved by the VA St. Louis Health Care System Institutional Review Board (protocol no. 1606333).

Reporting summary

Further information on research design is available in the Nature Research Reporting Summary linked to this article.

Data availability

The data that support the findings of this study are available from the US Department of Veterans Affairs. VA data are made freely available to researchers behind the VA firewall with an approved VA study protocol. For more information, visit or contact the VA Information Resource Center at

Code availability

The analytic code is available at


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Long COVID after mild SARS-CoV-2 infection: Persistent heart inflammation might explain heart symptoms

Authors: Goethe University Frankfurt am Main Nature Medicine September 3,2022

After recovering from a SARS-CoV-2 infection, many people complain of persistent heart complaints, such as poor exercise tolerance, palpitations or chest pain, even if the infection was mild and there were no known heart problems in the past. Earlier studies, predominantly among young, physically fit individuals, were already able to show that mild cardiac inflammation can occur after COVID-19. However, the underlying cause of persistent symptoms, and whether this changes over time, was unknown.

A team of medical scientists led by Dr. Valentina Puntmann and Professor Eike Nagel from the Institute for Experimental and Translational Cardiovascular Imaging at University Hospital Frankfurt followed up with 346 people—half of them women—between the age of 18 and 77 years, in each case around 4–11 months after the documented SARS-CoV-2 infection. For this purpose, the team analyzed the study participants’ blood, conducted heart MRIs, and recorded and graded their symptoms using standardized questionnaires.

At the beginning of the study, 73% reported heart problems; for 57% these symptoms persisted 11 months after the SARS-CoV-2 infection. The research team measured mild but persistent heart inflammation that was not accompanied by structural changes in the heart. Blood levels of troponin—a protein that enters the blood when the heart muscle is damaged—were also unremarkable.

Dr. Puntmann, who led the Impression COVID&Heart Study, explains, “The patients’ symptoms match our medical findings. It is important to note that although triggered by the SARS-CoV-2 virus, the post-COVID cardiac inflammatory involvement differs considerably from classic viral myocarditis. Extensive damage of the heart muscle leading to structural heart changes or impaired function are not characteristic at this stage of disease evolution.”

Long COVID after mild SARS-CoV-2 infection: Persistent heart inflammation might explain heart symptoms
Representative magnetic resonance images of a symptomatic patient. (a-f) Late gadolinium enhancement imaging (A, D-F) and Native T1 (B) and T2 (C) mapping measurements of a 57-year-old woman evaluated 201 days after COVID-19 infection. This individual reported dyspnea, palpitations, and chest pain, worsening on minimal exertion. Late gadolinium enhancement imaging allows to visualize regional accumulation of the gadolinium-based contrast agent along the outer rim of the myocardial free wall (red arrows), as well as within the thickened pericardial layers, separated by small amounts of pericardial effusion (blue arrows). Credit: Nature Medicine (2022). DOI: 10.1038/s41591-022-02000-0

The clinical picture is more reminiscent, she says, of the findings in chronic diffuse inflammatory syndromes such as autoimmune conditions. “Although most likely driven by a virus-triggered autoimmune process, a lot more research is needed in order to understand the underlying pathophysiology. Similarly, the long-term effects of cardiac inflammation following a mild COVID infection need to be clarified in future studies.”

Because the study is restricted to a selected group of individuals who took part because they had symptoms, the prevalence of findings cannot be extrapolated to the population as a whole. The study appears in Nature Medicine.

A Key to Long Covid Is Virus Lingering in the Body, Scientists Say

Virus remaining in some people’s bodies for a long time may be causing longer-term complications, recent research suggests

Authors:  Sumathi Reddy Sept. 8, 2022 The Wall Street Journal

The virus that causes Covid-19 can remain in some people’s bodies for a long time.  A growing number of scientists think that lingering virus is a root cause of long Covid.

New research has found the spike protein of the SARS-CoV-2 virus in the blood of long Covid patients up to a year after infection but not in people who have fully recovered from Covid. Virus has also been found in tissues including the brain, lungs, and lining of the gut, according to scientists and studies 

The findings suggest that leftover reservoirs of virus could be provoking the immune system in some people, causing complications such as blood clots and inflammation, which may fuel certain long Covid symptoms, scientists say. 

A group of scientists and doctors are joining forces to focus research on viral persistence and aim to raise $100 million to further the search for treatments. Called the Long Covid Research Initiative, the group is run by the PolyBio Research Foundation, a Mercer Island, Wash., based nonprofit focused on complex chronic inflammatory diseases. 

“We really want to understand what’s at the root of [long Covid] and we want to focus on that,” says Amy Proal, a microbiologist at PolyBio and the initiative’s chief scientific officer. Dr. Proal has devoted her career to researching chronic infections after developing myalgic encephalomyelitis/chronic fatigue syndrome, an illness that shares similar symptoms with long Covid, in her 20s.  She has mostly recovered now but has symptoms she manages.

Three long Covid patients, frustrated at the lack of answers and treatments, have helped connect researchers. 

“Long Covid is this really incredible emergency,” says Henry Scott-Green, one of the patients, a 28-year-old in London who says brain fog, extreme fatigue and other debilitating long Covid symptoms prevented him from resuming full-time work as a product manager, though he plans to return soon. “We’re really trying to run really efficiently and cut out as many layers of bureaucracy as possible.”

So far, the group says it has received a pledge of $15 million from Balvi, an investment and direct giving fund established by Vitalik Buterin, the co-creator of the cryptocurrency platform Ethereum. een says debilitating long Covid symptoms have prevented him from resuming full-time work.

Among the strongest evidence of viral persistence in long Covid patients is a new study by Harvard researchers published Friday in the journal of Clinical Infectious Diseases. Researchers detected the spike protein of the SARS-CoV-2 virus in a large majority of 37 long Covid patients in the study and found it in none of 26 patients in a control group.

Patients’ blood was analyzed up to a year after initial infection, says David R. Walt, a professor of pathology at Brigham and Women’s Hospital in Boston and Harvard Medical School and lead researcher of the study. Dr. Walt isn’t currently involved with the long Covid initiative. 

A year after infection, some patients had levels of viral spike protein that were as high as they did earlier in their illness, Dr. Walt says. Such levels long after initial infection suggest that a reservoir of active virus is continuing to produce the spike protein because the spike protein typically doesn’t have a long lifetimehe adds.

Dr. Walt plans to test antivirals such as Paxlovid or remdesivir to see if the drugs help clear the virus and eliminate spike protein from the blood.  He says it’s possible that for some people, the normal course of medication isn’t enough to clear the virus. Such cases may require “a much longer exposure to these antivirals to fully clear,” says Dr. Walt.

One of the research group’s goals is to find a way for people to identify whether they continue to have the virus in their bodies. There is no easy way to determine this now. 

Long Covid patients experience such a wide range of long-term symptoms that scientists think there is likely more than one cause, however. Some cases may be fueled by organ damage, for instance. 

Yet consensus is growing around the idea that lingering virus plays a significant role in long Covid. Preliminary research from immunologist Akiko Iwasaki’s laboratory at Yale University documented T or B cell activity in long Covid patients’ blood, suggesting that patients’ immune systems are continuing to react to virus in their bodies. Dr. Iwasaki is a member of the new initiative. 

In a 58-person study published in the Annals of Neurology in March, University of California, San Francisco researchers also found SARS-CoV-2 proteins circulating in particles in long Covid patients’ blood, especially in those with symptoms such as fatigue and trouble concentrating.

Now, the group is completing a study using imaging techniques and tissue biopsies to detect persistent virus or reactivation of other viruses in tissue. It also is looking at T-cell immune responses in tissues and whether they correlate with symptoms. 

Some people may harbor the virus and don’t have long-term symptoms, says Timothy Henrich, an associate professor of medicine at UCSF involved with the study and a member of the long Covid initiative. For others, lingering virus may produce problems.

“I think there’s a real amount of mounting evidence that really suggests that there is persistent virus in some people,” says Dr. Henrich.

Unraveling the Interplay of Omicron, Reinfections, and Long Covid

Authors:  Liz Szabo AUGUST 26, 2022 KHN

The latest covid-19 surge, caused by a shifting mix of quickly evolving omicron subvariants, appears to be waning, with cases and hospitalizations beginning to fall.

Like past covid waves, this one will leave a lingering imprint in the form of long covid, an ill-defined catchall term for a set of symptoms that can include debilitating fatigue, difficulty breathing, chest pain, and brain fog.

Although omicron infections are proving milder overall than those caused by last summer’s delta variant, omicron has also proved capable of triggering long-term symptoms and organ damage. But whether omicron causes long covid symptoms as often — and as severe — as previous variants is a matter of heated study.

Michael Osterholm, director of the University of Minnesota’s Center for Infectious Disease Research and Policy, is among the researchers who say the far greater number of omicron infections compared with earlier variants signals the need to prepare for a significant boost in people with long covid. The U.S. has recorded nearly 38 million covid infections so far this year, as omicron has blanketed the nation. That’s about 40% of all infections reported since the start of the pandemic, according to the Johns Hopkins University Coronavirus Research Center.

Long covid “is a parallel pandemic that most people aren’t even thinking about,” said Akiko Iwasaki, a professor of immunobiology at Yale University. “I suspect there will be millions of people who acquire long covid after omicron infection.”

Scientists have just begun to compare variants head to head, with varying results. While one recent study in The Lancet suggests that omicron is less likely to cause long covid, another found the same rate of neurological problems after omicron and delta infections.

Estimates of the proportion of patients affected by long covid also vary, from 4% to 5% in triple-vaccinated adults to as many as 50% among the unvaccinated, based on differences in the populations studied. One reason for that broad range is that long covid has been defined in widely varying ways in different studies, ranging from self-reported fogginess for a few months after infection to a dangerously impaired inability to regulate pulse and blood pressure that may last years.

Even at the low end of those estimates, the sheer number of omicron infections this year would swell long-covid caseloads. “That’s exactly what we did find in the UK,” said Claire Steves, a professor of aging and health at King’s College in London and author of the Lancet study, which found patients have been 24% to 50% less likely to develop long covid during the omicron wave than during the delta wave. “Even though the risk of long covid is lower, because so many people have caught omicron, the absolute numbers with long covid went up,” Steves said.

recent study analyzing a patient database from the Veterans Health Administration found that reinfections dramatically increased the risk of serious health issues, even in people with mild symptoms. The study of more than 5.4 million VA patients, including more than 560,000 women, found that people reinfected with covid were twice as likely to die or have a heart attack as people infected only once. And they were far more likely to experience health problems of all kinds as of six months later, including trouble with their lungs, kidneys, and digestive system.

“We’re not saying a second infection is going to feel worse; we’re saying it adds to your risk,” said Dr. Ziyad Al-Aly, chief of research and education service at the Veterans Affairs St. Louis Health Care System.

Researchers say the study, published online but not yet peer-reviewed, should be interpreted with caution. Some noted that VA patients have unique characteristics, and tend to be older men with high rates of chronic conditions that increase the risks for long covid. They warned that the study’s findings cannot be extrapolated to the general population, which is younger and healthier overall.

“We need to validate these findings with other studies,” said Dr. Harlan Krumholz, director of the Yale New Haven Hospital Center for Outcomes Research and Evaluation. Still, he added, the VA study has some “disturbing implications.”

With an estimated 82% of Americans having been infected at least once with the coronavirus as of mid-July, most new cases now are reinfections, said Justin Lessler, a professor of epidemiology at the University of North Carolina Gillings School of Global Public Health.

Of course, people’s risk of reinfection depends not just on their immune system, but also on the precautions they’re taking, such as masking, getting booster shots, and avoiding crowds.

New Jersey salon owner Tee Hundley, 43, has had covid three times, twice before vaccines were widely available and again this summer, after she was fully vaccinated. She is still suffering the consequences.

After her second infection, she returned to work as a cosmetologist at her Jersey City salon but struggled with illness and shortness of breath for the next eight months, often feeling like she was “breathing through a straw.”

She was exhausted, and sometimes slow to find her words. While waxing a client’s eyebrows, “I would literally forget which eyebrow I was waxing,” Hundley said. “My brain was so slow.”

When she got a breakthrough infection in July, her symptoms were short-lived and milder: cough, runny nose, and fatigue. But the tightness in her chest remains.

“I feel like that’s something that will always be left over,” said Hundley, who warns friends with covid not to overexert. “You may not feel terrible, but inside of your body there is a war going on.”

Although each omicron subvariant has different mutations, they’re similar enough that people infected with one, such as BA.2, have relatively good protection against newer versions of omicron, such as BA.5. People sickened by earlier variants are far more vulnerable to BA.5.

Several studies have found that vaccination reduces the risk of long covid. But the measure of that protection varies by study, from as little as a 15% reduction in risk to a more than 50% decrease. A study published in July found the risk of long covid dropped with each dose people received.

For now, the only surefire way to prevent long covid is to avoid getting sick. That’s no easy task as the virus mutates and Americans have largely stopped masking in public places. Current vaccines are great at preventing severe illness but do not prevent the virus from jumping from one person to the next. Scientists are working on next-generation vaccines — “variant-proof” shots that would work on any version of the virus, as well as nasal sprays that might actually prevent spread. If they succeed, that could dramatically curb new cases of long covid.

“We need vaccines that reduce transmission,” Al-Aly said. “We need them yesterday.”

Could tiny blood clots cause long COVID’s puzzling symptoms?

Scientists debate evidence for a micro-clot hypothesis that has some people pursuing potentially risky treatments

Authors: Cassandra Willyard Nature 608, 662-664 (2022)doi:

When Lara Hawthorne, an illustrator in Bristol, UK, began developing strange symptoms after having COVID-19, she hoped that they weren’t due to the virus. Her initial illness had been mild. “I’ve been triple vaccinated. I felt quite protected,” she says. But months later, she was still sick with a variety of often debilitating symptoms: earaches, tinnitus, congestion, headaches, vertigo, heart palpitations, muscle pain and more. On some days, Hawthorne felt so weak that she could not get out of bed. When she finally saw her physician, the diagnosis was what she had been dreading: long COVID.

Unable to find relief, she became increasingly desperate. After reading an opinion piece in The Guardian newspaper about how blood clots might be to blame for long COVID symptoms, Hawthorne contacted a physician in Germany who is treating people with blood thinners and a procedure to filter the blood. She hasn’t heard back yet — rumour has it that people stay on the waiting list for months — but if she has the opportunity to head there for these unproven treatments, she probably will. “I don’t want to wait on my health when I’m feeling so dreadful,” she says.

Researchers are baffled by long COVID: hundreds of studies have tried to unpick its mechanism, without much success. Now some scientists, and an increasing number of people with the condition, have been lining up behind the as-yet-unproven hypothesis that tiny, persistent clots might be constricting blood flow to vital organs, resulting in the bizarre constellation of symptoms that people experience.

Heart disease after COVID: what the data say

Proponents of the idea (#teamclots, as they sometimes refer to themselves on Twitter) include Etheresia Pretorius, a physiologist at Stellenbosch University in South Africa, and Douglas Kell, a systems biologist at the University of Liverpool, UK, who led the first team to visualize micro-clots in the blood of people with long COVID. They say that the evidence implicating micro-clots is undeniable, and they want trials of the kinds of anticoagulant treatment that Hawthorne is considering. Pretorius penned the Guardian article that caught Hawthorne’s attention.

But many haematologists and COVID-19 researchers worry that enthusiasm for the clot hypothesis has outpaced the data. They want to see larger studies and stronger causal evidence. And they are concerned about people seeking out unproven, potentially risky treatments.

When it comes to long COVID, “we’ve now got little scattered of bits of evidence”, says Danny Altmann, an immunologist at Imperial College London. “We’re all scuttling to try and put it together in some kind of consensus. We’re so far away from that. It’s very unsatisfying.”

Cascade of clots

Pretorius and Kell met about a decade ago. Pretorius had been studying the role of iron in clotting and neglected to cite some of Kell’s research. When he reached out, they began chatting. “We had a Skype meeting and then we decided to work together,” Pretorius says. They observed odd, dense clots that resist breaking down for years in people with a variety of diseases. The research led them to develop the theory that some molecules — including iron, proteins or bits of bacterial cell wall — might trigger these abnormal clots.

Blood clotting is a complex process, but one of the key players is a cigar-shaped, soluble protein called fibrinogen, which flows freely in the bloodstream. When an injury occurs, cells release the enzyme thrombin, which cuts fibrinogen into an insoluble protein called fibrin. Strands of fibrin loop and criss-cross, creating a web that helps to form a clot and stop the bleeding.

Under a microscope, this web typically resembles “a nice plate of spaghetti”, Kell says. But the clots that the team has identified in many inflammatory conditions look different. They’re “horrible, gunky, dark”, Kell says, “such as you might get if you half-boiled the spaghetti and let it all stick together.” Research by Kell, Pretorius and their colleagues suggests that the fibrin has misfolded1, creating a gluey, ‘amyloid’ version of itself. It doesn’t take much misfolding to seed disaster, says Kell. “If the first one changes its conformation, all the others have to follow suit”, much like prions, the infectious misfolded proteins that cause conditions such as Creutzfeldt–Jakob disease.

Long-COVID treatments: why the world is still waiting

Pretorius first saw these strange, densely matted clots in the blood of people with a clotting disorder2, but she and Kell have since observed the phenomenon in a range of conditions1 — diabetes, Alzheimer’s disease and Parkinson’s disease, to name a few. But the idea never gained much traction, until now.

When the pandemic hit in 2020, Kell and Pretorius applied their methods almost immediately to people who had been infected with SARS-CoV-2. “We thought to look at clotting in COVID, because that is what we do,” Pretorius says. Their assay uses a special dye that fluoresces when it binds to amyloid proteins, including misfolded fibrin. Researchers can then visualize the glow under a microscope. The team compared plasma samples from 13 healthy volunteers, 15 people with COVID-19, 10 people with diabetes and 11 people with long COVID3. For both long COVID and acute COVID-19, Pretorius says, the clotting “was much more than we have previously found in diabetes or any other inflammatory disease”. In another study4, they looked at the blood of 80 people with long COVID and found micro-clots in all of the samples.

So far, Pretorius, Kell and their colleagues are the only group that has published results on micro-clots in people with long COVID.

But in unpublished work, Caroline Dalton, a neuroscientist at Sheffield Hallam University’s Biomolecular Sciences Research Centre, UK, has replicated the results. She and her colleagues used a slightly different method, involving an automated microscopy imaging scanner, to count the number of clots in blood. The team compared 3 groups of about 25 individuals: people who had never knowingly had COVID-19, those who had had COVID-19 and recovered, and people with long COVID. All three groups had micro-clots, but those who had never had COVID-19 tended to have fewer, smaller clots, and people with long COVID had a greater number of larger clots. The previously infected group fell in the middle. The team’s hypothesis is that SARS-CoV-2 infection creates a burst of micro-clots that go away over time. In individuals with long COVID, however, they seem to persist.

Dalton has also found that fatigue scores seem to correlate with micro-clot counts, at least in a few people. That, says Dalton, “increases confidence that we are measuring something that is mechanistically linked to the condition”.

In many ways, long COVID resembles another disease that has defied explanation: chronic fatigue syndrome, also known as myalgic encephalomyelitis (ME/CFS). Maureen Hanson, who directs the US National Institutes of Health (NIH) ME/CFS Collaborative Research Center at Cornell University in Ithaca, New York, says that Pretorius and Kell’s research has renewed interest in a 1980s-era hypothesis about abnormal clots contributing to symptoms. Pretorius, Kell and colleagues found amyloid clots in the blood of people with ME/CFS, but the amount was much lower than what they’ve found in people with long COVID5. So clotting is probably only a partial explanation for ME/CFS, Pretorius says.

Micro-clot mysteries

Where these micro-clots come from isn’t entirely clear. But Pretorius and Kell think that the spike protein, which SARS-CoV-2 uses to enter cells, might be the trigger in people with long COVID. When they added the spike protein to plasma from healthy volunteers in the laboratory, that alone was enough to prompt formation of these abnormal clots6.

Bits of evidence hint that the protein might be involved. In a preprint7 posted in June, researchers from Harvard University in Boston, Massachusetts, reported finding the spike protein in the blood of people with long COVID. Another paper8 from a Swedish group showed that certain peptides in the spike can form amyloid strands on their own, at least in a test tube. It’s possible that these misfolded strands provide a kind of template, says Sofie Nyström, a protein chemist at Linköping University in Sweden and an author of the paper.

Micrographs of platelet poor plasma of a healthy volunteer showing few microclots,and post-COVID-19 infection showing microclots
Micro-clots (green) in a study participant before SARS-CoV-2 infection (left four panels) and in the same person after they developed long COVID (right four panels).Credit: E. Pretorius et al./Cardiovasc. Diabetol. (CC BY 4.0)

A California-based group found that fibrin can actually bind to the spike. In a 2021 preprint9, it reported that when the two proteins bind, fibrin ramps up inflammation and forms clots that are harder to degrade. But how all these puzzle pieces fit together isn’t yet clear.

If the spike protein is the trigger for abnormal clots, that raises the question of whether COVID-19 vaccines, which contain the spike or instructions for making it, can induce them as well. There’s currently no direct evidence implicating spike from vaccines in forming clots, but Pretorius and Kell have received a grant from the South African Medical Research Council to study the issue. (Rare clotting events associated with the Oxford–AstraZeneca vaccine are thought to happen through a different mechanism (Nature 596, 479–481; 2021).)

Raising safety concerns about the vaccines can be uncomfortable, says Per Hammarström, a protein chemist at Linköping University and Nyström’s co-author. “We don’t want to be over-alarmist, but at the same time, if this is a medical issue, at least in certain people, we have to address that.” Gregory Poland, director of the Mayo Clinic’s vaccine research group in Rochester, Minnesota, agrees that it’s an important discussion. “My guess is that spike and the virus will turn out to have a pretty impressive list of pathophysiologies,” he says. “How much of that may or may not be true for the vaccine, I don’t know.”

Dearth of data

Many researchers find it plausible and intriguing that micro-clots could be contributing to long COVID. And the hypothesis does seem to fit with other data that have emerged on clotting. Researchers already know that people with COVID-19, especially severe disease, are more likely to develop clots. The virus can infect cells lining the body’s 100,000 kilometres of blood vessels, causing inflammation and damage that triggers clotting.

Those clots can have physiological effects. Danny Jonigk, a pathologist at Hanover Medical School in Germany, and his colleagues looked at tissue samples from people who died of COVID-19. They found micro-clots and saw that the capillaries had split, forming new branches to try to keep oxygen-rich blood flowing10. The downside was that the branching introduces turbulence into the flow that can give rise to fresh clots.

How common is long COVID? Why studies give different answers

Several other labs have found signs that, in some people, this tendency towards clotting persists months after the initial infection. James O’Donnell, a haematologist and clotting specialist at Trinity College Dublin, and his colleagues found11 that about 25% of people who are recovering from COVID-19 have signs of increased clotting that are “quite marked and unusual”, he says.

What is less clear is whether this abnormal clotting response is actually to blame for any of the symptoms of long COVID, “or is it just, you know, another unusual phenomenon associated with COVID?” O’Donnell says.

Alex Spyropoulos, a haematologist at the Feinstein Institutes for Medical Research in New York City, says the micro-clot hypothesis presents “a very elegant mechanism”. But he argues that much more work is needed to tie the lab markers to clinical symptoms. “What’s a little bit disturbing is that these authors and others make huge leaps of faith,” Spyropoulos says.

Jeffrey Weitz, a haematologist and clotting specialist at McMaster University in Hamilton, Canada, points out that the method Pretorius’s team is using to identify micro-clots “isn’t a standard technique at all”. He adds: “I’d like to see confirmation from other investigators.” Micro-clots are difficult to detect. Pathologists can spot them in tissue samples, but haematologists tend to look for markers of abnormal clotting rather than the clots themselves.

Other, larger studies of long COVID have failed to find signs of clotting. Michael Sneller, an infectious-disease specialist, and his colleagues at the NIH in Bethesda, Maryland, thoroughly examined 189 people who had been infected with SARS-CoV-2, some with lingering symptoms and some without, and 120 controls12. They did not specifically look for micro-clots. But if micro-clots had been clogging the capillaries, Sneller says, they should have seen some evidence — tissue damage in capillary-rich organs such as the lungs and kidneys, for example. Micro-clots might also damage red blood cells, leading to anaemia. But Sneller and his colleagues found no signs of this in any of the lab tests.

The four most urgent questions about long COVID

Kell and Pretorius argue that just because this study didn’t find any evidence of micro-clots doesn’t mean they aren’t there. One of the key issues with long COVID is that “every single test comes back within the normal ranges”, Pretorius says. “You have desperately ill patients with no diagnostic method.” She hopes that other researchers will read their papers and attempt to replicate their results. “Then we can have a discussion,” she says. The ultimate causal proof, she adds, would be people with long COVID feeling better after receiving anticoagulant therapies.

There is some limited evidence of this. In an early version of a preprint, posted in December 2021, Kell, Pretorius and other researchers, including physician Gert Jacobus Laubscher at Stellenbosch University, reported that 24 people who had long COVID and were treated with a combination of two antiplatelet therapies and an anticoagulant experienced some relief13. Participants reported that their main symptoms resolved and that they became less fatigued. They also had fewer micro-clots. Pretorius and Kell are working to gather more data before they try to formally publish these results. But other physicians are already using these medications to treat people with long COVID. Some are even offering a dialysis-like procedure that filters fibrinogen and other inflammatory molecules from the blood. To O’Donnell, such treatment feels premature. He accepts that some people with long COVID are prone to clots, but leaping from a single small study to treating a vast number of people is “just not going to wash in 2022 in my book”, he says. Sneller agrees. “Anticoagulating somebody is not a benign thing. You basically are interfering with the blood’s ability to clot,” he says, which could make even minor injuries life-threatening.

Kell says he’s tired of waiting for a consensus on how to treat long COVID. “These people are in terrible pain. They are desperately unwell,” he says. Altmann understands that frustration. He gets e-mails almost daily, asking: “Where are the drug trials? Why does it take so long?” But even in the midst of a pandemic, he argues, researchers have to follow the process. “I’m not rubbishing anybody’s data. I’m just saying we’re not there yet,” he says. “Let’s join up the dots and do this properly.”


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Opinions | How long covid reshapes the brain — and how we might treat it

Authors: Wes Ely August 25, 2022 The Washington Post

The young man pulled something from behind both ears. “I can’t hear anything without my new hearing aids,” said the 32-year-old husband and father. “My body is broken, Doc.” Once a fireman and emergency medical technician, he’d had covid more than 18 months before and was nearly deaf. He was also newly suffering from incapacitating anxiety, cognitive impairment and depression. Likewise, a 51-year-old woman told me through tears: “It’s almost two years. My old self is gone. I can’t even think clearly enough to keep my finances straight.” These are real people immersed in the global public health catastrophe of long covid, which the medical world is struggling to grasp and society is failing to confront.

As such stories clearly indicate, covid is biologically dangerous long after the initial viral infection. One of the leading hypotheses behind long covid is that the coronavirus is somehow able to establish a reservoir in tissues such as the gastrointestinal tract. I believe the explanation for long covid is more sinister.

The science makes it increasingly clear that covid-19 turns on inflammation and alters the nervous system even when the virus itself seems to be long gone. The virus starts by infecting nasal and respiratory lining cells, and the resulting inflammation sends molecules through the blood that trigger the release of cytokines in the brain. This can happen even in mild covid cases. Through these cell-to-cell conversations, cells in the nervous system called microglia and astrocytes are revved up in ways that continue for months — maybe years. It’s like a rock weighing down on the accelerator of a car, spinning its engine out of control. All of this causes injury to many cells, including neurons. It is past time we recognized this fact and began incorporating it into the ways we care for those who have survived covid.

For too long, the mysteries of long covid led many health-care professionals to dismiss it as an untreatable malady or a psychosomatic illness without a scientific basis. Some of this confusion comes down to the stuttering cadence of scientific progress. Early in the pandemic, autopsy findings from patients who died of covid “did not show encephalitis or other specific brain changes referable to the virus” as one report noted. Patients with profound neurological illnesses resulting from covid-19 had no trace of the virus in the cerebrospinal fluid encasing their brains.

These studies left most medical professionals mistakenly convinced that the virus was not damaging the brain. Accordingly, we narrowed our focus to the lungs and heart and then scratched our heads in wonder at the coma and delirium found in more than 80 percent of covid ICU patients. A robust study from the Netherlands showed that at least 12.5 percent of covid patients end up with long covid three months afterward, yet because “brain fog” wasn’t identified until later in the pandemic, these investigators didn’t include cognitive problems or mental health disorders in the data they collected. Thus, this otherwise beautifully executed study almost certainly underestimated the rate of long covid.

Since the early days of the pandemic, we’ve learned a great deal about the neurological effects of SARS-CoV-2. Earlier this year, the UK Biobank neuroimaging study showed that even mild covid can lead to an overall reduction in the size of the brain, with notable effects in the frontal cortex and limbic system. These findings help explain the profound anxiety, depression, memory loss and cognitive impairment experienced by so many long-covid patients.

new study published in the Lancet of more than 2.5 million people matched covid-19 patients with non-covid patients to determine the rate of recovery from mental health complaints and neurological deficits like the depression and brain fog in my own patients. What it revealed is partly encouraging and partly devastating: The anxiety and mood disorders in long covid tend to resolve over months, while serious dementia-like problems, psychosis and seizures persist at two years.

Over 2 Million Americans Aren’t Working Due to Long Covid

Brookings Institution report says the loss of work translates into roughly $170 billion a year in lost wages

Authors: Sumathi Reddy August 25, 2022 The Wall Street Journal

Between two million and four million Americans aren’t working due to the long-term effects of Covid-19, according to a new Brookings Institution report released Wednesday.

The inability to work translates to roughly $170 billion a year in lost wages, the report estimates. It follows a January Brookings Institution report that estimated long Covid was potentially causing 15% of the country’s labor shortage.

The report estimates that roughly 16 million Americans of working age—between 18 and 65—have long Covid, which most groups and doctors define as wide-ranging symptoms that persist for months following an infection and can include shortness of breath, extreme fatigue and neurocognitive issues. 

An estimated 10% to 30% of people with Covid develop the condition, according to studies and estimates from governments, hospitals, universities and doctors. It can occur after even mild cases. Long Covid’s impact is being felt on workplaces with employees not well enough to work and patients struggling to financially support themselves, as well as family members having to act as caregivers. 

“Three million full-time-equivalent workers is 1.8% of the entire U.S. civilian labor force,” said Katie Bach, a nonresident senior fellow at the Washington, D.C.-based think tank and author of both Brookings reports. 

A roughly 1.8% reduction in the U.S. workforce is in line with estimates from other countries. In a May speech a former Bank of England committee member attributed a 1.3% drop in labor-force participation to “long-term sickness,” citing long Covid.

Ms. Bach said she used data from the U.S. Census Bureau, which recently added four long-Covid questions to its June household survey. She also used a recent Federal Reserve Bank of Minneapolis study, a survey from the United Kingdom’s Trades Union Congress, and a Lancet study from a long Covid advocacy group for the report.

David Cutler, a health economist and professor of economics at Harvard University, has also calculated the economic cost of long Covid. According to his estimates, the total cost is $3.7 trillion. 

He breaks the costs down to reduced quality of life, reduced earnings and increased medical spending.

“So if you say, is it worth it to spend $50 billion on long Covid…there’s almost no amount of money that you could spend that you could feel like is too much money,” said Dr. Cutler.

Dr. Cutler, who has reviewed Ms. Bach’s reports and said they are based on sound calculations, agreed that long Covid is contributing to a labor shortage. The labor force is roughly 600,000 workers smaller than in early 2000 and several million smaller if you adjust for the increase in population, according to Labor Department data. 

Ms. Bach noted that the number of disabled people in the U.S. has gone up by two million during the pandemic, according to the Census Bureau’s current population survey. Yet labor-force participation among the disabled has gone up, which may mean some long Covid patients are working in some capacity remotely. 

David Putrino, director of rehabilitation innovation at Mount Sinai Health System in New York City, said the Brookings report highlights what doctors see at long Covid clinics all the time. 

“Long Covid definitely affects the ability to remain employed, and we’re definitely seeing a lot of people being denied short- and long-term disability and workers’ compensation despite the fact that they have a diagnosis of long Covid,” said Dr. Putrino.

Monica Verduzco-Gutierrez, professor and chair of the department of rehabilitation medicine at the University of Texas Health Science Center at San Antonio and director of its Covid Recovery Clinic, said a lot of long Covid patients are having difficulties going back to work. 

“That’s going to cost the economy a lot,” she said. “Study after study shows that a lot of the people who are affected are 40-year-olds, people who are working.”