How many times can you get COVID? What experts know about reinfection

Authors:  Hannah Sparks May 18, 2022  The New York Post

The new normal is now.

In what seemed like an instant, COVID-19 became an inevitable aspect of everyday life more than two years ago — with no signs to suggest that we’ll ever see otherwise again.

As we look at our lives ahead with waves of new variants and “stealth” sub-variants, and seasonal vaccine boosters to match, it begs the question: Should we fear reinfection?

Doctors have recently confirmed that those infected with an earlier Omicron variant, which first appeared and spread rapidly last summer, can indeed test positive again for the new sub-variant.

Last week, as the latest strain — BA.2 or BA2.12.1 — made its presence known in New York City and clusters throughout the Northeast and Midwest, the US crossed a grim milestone: 1,000,000 COVID deaths. Globally, we’ve lost more than 6,000,000.

The Post spoke to NYU Langone Health infectious diseases expert Dr. Michael Phillips about what we can expect from life with COVID as we know it.

Can you get infected with COVID twice — and who’s at risk?

There is no such thing as perfect immunity from COVID. Regardless of severity or immunization, someone who tests positive for the virus can become infected again at some point.

“Our hospitalizations have crept up over the past several weeks, particularly with this newer variant of Omicron,” Dr. Phillips told The Post. “But thankfully, the vast majority of people [who] get the infection tend to recover without too much problems.”

But there’s more at stake for some. People who have not received two doses of the mRNA vaccine, as well as those with weakened immune systems due to age, medications, preexisting illness or other clinical factors, such as poor physical fitness, are at a higher risk of reinfection and becoming severely sick with COVID-19.

But Phillips warns against us “develop[ing] a laissez faire attitude about it.” While some relatively young, healthy and vaccinated individuals may become reinfected with only a mild case, the person they pass it to — potentially, someone with a weakened immune system due to age, medications, preexisting illness or other clinical factors, such as poor physical fitness — may not fare so well.

Omicron is “very, very different from prior waves of Delta,” Phillips added. “I think it shifted our game plan for sure.” Now more than ever the focus of prevention efforts is on protecting those the ones at a greater risk of severe illness — and protecting yourself from COVID reinfection means also “protect[ing] the vulnerable.”

Can you be reinfected with the same COVID variant?

It’s certainly possible, particularly in those who are not vaccinated. Unlike earlier variants, Omicron has rapidly evolved into several sub-types, prompting simultaneous localized outbreaks. Meanwhile, there’s no telling how many positive cases of COVID-19 go unreported, whether due to lack of testing or symptoms to warrant alarm. So whether to fear reinfection with the same niche strain may not be a pragmatic question to ask — because, by the time it’s answered, a new strain may already be here.

“There are so many of these other variants within that big family of coronaviruses, and we’re typically infected with three to four a year,” Phillips explained, most of which present as a mild cold.

Ideally, SARS-CoV-2 could fade into coronavirus obscurity like many of the others — but we aren’t there yet, and it’s too soon to say whether that’s a feasible outlook. “It’s still severe enough that that we have to be pretty mindful about,” said Phillips. “We just don’t know enough about future variants for us to take our guard down yet.”

How long after getting COVID can you be reinfected?

This is another complicated question — especially for sufferers of long COVID, who appear to harbor low, even undetectable levels of the virus for weeks and months. For mild to moderate cases, people who test positive for COVID can expect their infection to clear within five to 10 days after their symptoms arose, or since their confirmed test result.

Nascent research suggests that the average immune system can fend off COVID reinfection for three to five months after the previous bout. That’s why, according to the Centers for Disease Control and Prevention, people who had a confirmed infection within the previous 90 days are not expected to quarantine after coming in contact with another infected individual.

But all bets are off about six months later, when antibodies are known to start waning — regardless of vaccination.

How long do COVID antibodies last?

Experts don’t know exactly. While those survive COVID appear to be largely protected from repeat or severe illness for up to five months after the previous infection, there isn’t enough data available yet to be certain how long those COVID-specific antibodies linger, or even to confirm that the presence of antibodies guarantees immunity, according to the Food and Drug Administration.

Immune system B cells give rise to COVID-specific antibodies, designed to attack the virus on sight, before it can penetrate tissue cells and reproduce. They begin to form within the first few days infection or vaccination, and continue to build for several weeks until they peak at around three months thereafter — when your COVID defenses are at their strongest.

The good news is that waning antibodies doesn’t mean we’re totally defenseless, as some B cells will remember the tools it previously took to create COVID antibodies during re-invasion. (Boosters, furthermore, helps our immune system remember how. to fight.) Meanwhile, our killer T-cells, the immune system’s backup line of defense, may not so good at preventing the virus from entering the body, but they can spot an infected host cell — and destroy before it multiplies to another cell. And while they’re more difficult to track, they do appear to be more faithful than fleeting antibodies.

“Those appear to stay be much more robust,” said Phillips, adding, that “the T cell response is probably more important for response to viral infections” in the long run.

Are COVID vaccines still effective?

“We don’t have to be paranoid about the emergence of a new strain … but we have to be thoughtful and ready for that.”

Dr. Michael Phillips, MD, NYU Langone Health

More or less. Vaccines remain the best way to build-up antibodies, the body’s primary line of defense against severe COVID-19 illness. While allowing oneself to become infected can also give rise to antibodies, it’s not worth the risk.

“I’m strongly pro vaccine, because of the the problems that happen when you don’t get it,” said Phillips, who hinted at alternative forms of vaccination technology on the horizon as well.

Regardless of type, antibodies are known to wane afer about six months since last infection or booster, making reinfection more likely to occur.

How often can you get a COVID booster?

For those on the two-dose regimen, a second round should be completed about six weeks after the first. However, it’s been well over a year since the vaccine was introduced, which means many patients completed those two rounds back in 2021.

Doctors expect that annually, even seasonally redesigned boosters against COVID-19 could become the norm — kind of like influenza, only different, and more troubling: One flu season sees just one or two major strains globally, allowing researchers time to prepare vaccines. “It’s not this, sort of, constant changing during a ‘season’,” said Phillips, like COVID-19 has done.

Currently, only those who have a weakened immune system and people age 50 or older are being recommended for a third shot by the CDC — which is, altogether, a good sign.

Said Phillips, “We don’t have to be paranoid about the emergence of a new strain … but we have to be thoughtful and ready for that.”

What You Should Know About Treating Covid-19

Some therapies have been shown to work in clinical studies and other research

Authors: Jared S. Hopkins Mar. 21, 2022 4:47 pm ET The Wall Street Journal

The Food and Drug Administration authorized the first antiviral pills to treat Covid-19 from Pfizer Inc. and Merck & Co. and partner Ridgeback Biotherapeutics LP in December. The authorizations came after each drugmaker’s pill received a positive recommendation from a panel of experts advising the FDA, and weeks after the emergence of the Omicron variant.

Public-health experts say the best preventive measure to decrease the likelihood of contracting Covid-19 is to get vaccinated. The Centers for Disease Control and Prevention has recommended that everyone 12 and older get an additional shot after completing a primary series of Covid-19 vaccination.

Here’s what public-health and infectious-disease experts say about how to treat Covid-19.

I’ve contracted Covid-19; what should I do? How can I treat mild symptoms from home?

Doctors say an initial step is to monitor symptoms to determine whether infected people could be considered at low or high risk for developing severe disease. Individuals who are typically considered to be at low risk for severe disease include people who are young and healthy. They should stay at home away from others, drink plenty of fluids to stay hydrated and take over-the-counter medicines such as acetaminophen or ibuprofen to reduce fevers, according to physicians and the CDC. Physicians say people who are young, otherwise healthy and at low risk of developing severe disease should recover if they take the right steps. 

People who are at high risk include those with underlying health conditions and the elderly, according to doctors. These individuals should pay close attention to any change in their health, including symptoms of fever, cough, fatigue or difficulty breathing. If high-risk individuals need medical attention, they should seek it right away.

“The management of Covid continues to depend on what your risk of progression is,” said Carlos del Rio, a professor of global health at Emory University. “Treatment has to be individualized.” 

Additionally, people who are vaccinated and become infected—what is known as a breakthrough case—are unlikely to develop severe disease or need hospitalization, according to doctors and studies.

What are Covid-19 antiviral pills? When can I get one to treat myself?

Antivirals are treatments designed to impede a virus’s replication cycle, allowing people to recover from the illness, and they are most effective if they are taken by patients early in the course of disease. 

Merck and partner Ridgeback say their oral antiviral, molnupiravir, reduced the risk of hospitalization and death by about 30%. Pfizer said in December a late-stage study confirmed its oral antiviral, called Paxlovid, which is taken with another antiviral called ritonavir, was 89% effective at reducing the risk of hospitalization and death in adults at high risk of severe Covid-19. A separate, preliminary analysis found that the drug may also help people at low risk of severe Covid-19. The company said lab tests showed Paxlovid works against the Omicron variant. 

Both drugs are authorized by the FDA, and have been cleared for use. 

The pills carry some safety risks and limitations. A component of Pfizer’s Paxlovid regimen, ritonavir, can interact with other drugs in dangerous or life-threatening ways. Drugs that interact with Paxlovid include common ones such as the cholesterol-lowering pill simvastatin, the antipsychotic lurasidone and the sedative triazolam. Patients should make sure to tell their doctor or pharmacist of any medications they take before starting an antiviral regimen from Pfizer, according to physicians. The Merck-Ridgeback drug isn’t authorized for children because of its potential effect on bone and cartilage growth. It isn’t recommended for pregnant women because of the potential for fetal harm, a safety signal seen in animal studies of the drug.

The Merck-Ridgeback drug can be prescribed by doctors to adults at high risk of severe disease shortly after they develop mild to moderate symptoms. Pfizer’s drug permits doctors to prescribe the medicine to high-risk patients age 12 and older early in the course of disease, shortly after they develop symptoms.

The companies studied their drugs in people who are at high risk of developing severe disease. They excluded certain people from their tests: Both left out pregnant women while Pfizer excluded people who take certain common medications such as heart drugs. 

The pills are also being tested in people for preventive use with results expected by mid-2022.

Both treatments are taken over five days, with Pfizer’s totaling 30 pills and Merck-Ridgeback clocking in at 40 capsules. 

The U.S. has purchased 20 million courses of treatment of Pfizer’s pill, although supply has been limited as the company increases manufacturing. The government purchased about 3.1 million courses of the Merck-Ridgeback pill, and Merck said all of it has been supplied.

Will antiviral pills be effective against the Omicron variant?

The antiviral manufacturers say they expect the treatments to be effective against Omicron, although they plan to conduct tests to verify. Both drugs target different parts of the virus than vaccines and other treatments, which are targeting the spike protein that plays a key role in infecting cells. 

Pfizer has said so far its researchers haven’t seen any changes in the variant that suggests Paxlovid, which is given with the antiviral ritonavir, is less effective than against previous strains. The company said in January that three separate lab tests showed Paxlovid is effective against the Omicron.

Merck said last year that it was working to collect samples of Omicron to study whether molnupiravir is effective against Omicron and expected results by the end of the year. It has not announced results from any internal testing

Molnupiravir targets machinery the virus uses to replicate, rather than the spike protein, the structure that helps the virus infiltrate cells.

Merck expects molnupiravir to be effective against Omicron because testing has found the drug to be effective against other circulating variants. “Molnupiravir retains activity across all of these variants of concern, and there’s no difference in its antiviral activity,” said Daria Hazuda, vice president of infectious disease discovery at Merck. “There shouldn’t be any more or less concern about its effectiveness against Omicron versus any other variants.”

Merck and partner Ridgeback said in January that molnupiravir was active against Omicron in laboratory tests, pointing to six preclinical studies performed by researchers outside the company.

Are there any drugs approved or authorized for administration in clinics?

Monoclonal antibody treatments are available for people who develop symptoms and are considered to be at high risk of severe disease. As many as 75% of U.S. adults are eligible to take the drugs under FDA guidelines, according to experts. The drugs are lab-engineered molecules that mimic the natural antibodies produced by the immune system to fight off viruses. They are usually administered by infusion or injection at hospitals or clinics.

“It’s a lot easier to access one of these if you happen to live in a more populous area,” said Erica Johnson, chair of the Infectious Disease Board of the American Board of Internal Medicine and assistant professor of infectious diseases at Johns Hopkins University School of Medicine.

The FDA is permitting use of antibody treatments from Eli Lilly & Co., and from GlaxoSmithKline PLC and partner Vir Biotechnology. In January the agency restricted use of older antibody drugs from Lilly and Regeneron Pharmaceuticals because tests found they lost potency against the Omicron variant.

The Glaxo-Vir drug, sotrovimab, has retained effectiveness against Omicron. Regulators cleared for use in February a new drug from Lilly called bebtelovimab that retains effectiveness against Omicron, for the treatment of mild to moderate Covid-19 in nonhospitalized individuals 12 and older who are at high risk of getting severely sick.

In some parts of the U.S., the antibody treatments may be available for administration at home or through mobile clinics. Some states are also allowing low-risk patients to receive monoclonal antibodies, but it is not recommended by the National Institutes of Health. “The juice is not worth the squeeze,” Dr. del Rio said. 

Evusheld, a preventive antibody cocktail from AstraZeneca PLC, which has shown strong efficacy in reducing risk of symptomatic Covid-19, was authorized by the FDA on Dec. 8. Evusheld is delivered as two shots and aims to offer an alternative to vaccines primarily for a minority of adolescents and adults age 12 and older with moderate to severely compromised immune systems. That includes those who have cancer, another illness, or take medications or undergo treatments such as chemotherapy that inhibit an immune response to Covid-19 vaccines.

The FDA in January permitted the use of Veklury, also known as remdesivir, for treatment of people who are not hospitalized with Covid-19. The antiviral was first developed for treating Ebola

For patients with mild to moderate symptoms but who are at high risk of developing severe disease and becoming hospitalized, the National Institutes of Health says the first option should be Paxlovid. If the drug is unavailable, or the patient can’t take it for some reason, sotrovimab should be administered. Veklury is the third option, followed by molnupiravir.

My loved one is hospitalized. Are there any FDA-approved treatments for hospitalized Covid-19 patients?

Most research has found that monoclonal antibodies aren’t effective once people become hospitalized and they are currently not recommended at that point.

Veklury is fully approved for treatment of people who are hospitalized with Covid-19.

Patients who may be at risk of advancing to severe disease may also be given dexamethasone, a steroid first approved in the 1950s that is successful at treating inflammation. The steroid has been found in studies of hospitalized Covid-19 patients to reduce the risk of death. It is recommended for treatment by the NIH and the Infectious Diseases Society of America. 

Patients who don’t respond to dexamethasone may be given an immune-suppressing rheumatoid arthritis drug called Olumiant, which received an emergency-use authorization from the FDA after a study showed it helped hospitalized patients recover more quickly.

A similar rheumatoid arthritis drug, Actemra, made by Roche Holding AG, is also used to tamp down the potentially lethal inflammation seen in some hospitalized patients.

Doctors sometimes administer blood-thinners to hospitalized patients, which can reduce blood clots and inflammation that develop in some Covid-19 patients. Some studies have found that such treatments can also reduce the risk of patients needing mechanical ventilation and could help them leave the hospital sooner.

Which Covid-19 treatments are being tested?

Bristol-Myers Squibb Co. is testing a monoclonal antibody and expects Phase 2 results in the coming months, according to the company.

Researchers studying the antidepressant fluvoxamine recently reported in the Lancet, a peer-reviewed medical journal, that patients who took the widely available drug were significantly less likely to require hospitalization than those who didn’t. The drug is still being studied, and isn’t yet recommended by the NIH or IDSA. 

Some research has suggested steroid inhalers are helpful at reducing symptoms early in the course of the disease, said David Boulware, an infectious-diseases specialist at the University of Minnesota. He said it is unlikely manufacturers would seek an emergency use authorization because they are widely available, although the NIH and IDSA hasn’t recommended them.

An oral antiviral from Japanese drugmaker Shionogi & Co. is also in clinical trials.

Is ivermectin effective in treating Covid-19?

In the latest trial, researchers testing the antiparasitic drug ivermectin against Covid-19 found that the drug didn’t reduce hospital admissions. The trial, with nearly 1,400 Covid-19 patients at risk of severe disease, is the largest to show that those who received ivermectin as a treatment didn’t fare better than those who received a placebo.

Most prior research hasn’t shown that ivermectin is an effective Covid-19 treatment, physicians say, and the drug isn’t authorized for that use. The FDA has approved ivermectin to treat some parasitic worms, as well as a topical treatment for head lice and skin conditions such as rosacea. It is also used in the U.S. to treat or prevent parasites in animals.

The drug, which was developed years ago by Merck, has been used to prevent river blindness and other diseases in Africa and other places where parasites are common. Prescriptions of the drug have shot up in recent months, and federal health regulators have warned doctors and veterinarians against the unauthorized use of ivermectin to treat Covid-19. 

Can my doctor treat me with hydroxychloroquine?

Numerous studies have found that hydroxychloroquine and chloroquine, approved decades ago to treat and prevent malaria, don’t reduce the severity of Covid-19 symptoms or provide a benefit to patients. Doctors, however, are permitted to write so-called off-label prescriptions, to treat ailments that the FDA hasn’t approved, and some doctors have done so with hydroxychloroquine and chloroquine. 

The drugs, which are also used to treat ailments such as lupus and rheumatoid arthritis, initially received emergency-use authorization, although the FDA later revoked it after concluding the therapies were unlikely to help fight the disease. 

Early in the pandemic hospitals and doctors around the world began treating Covid-19 patients with hydroxychloroquine after several small studies suggested a benefit.

The NIH recommends against the use of hydroxychloroquine in hospitalized or nonhospitalized people, as does the IDSA, which also recommends against it as a prophylactic. 

I’m vaccinated but I contracted Covid-19. Can I use any of the approved treatments?

“Vaccination remains one of the most important factors for us to consider,” said Dr. Abhijit Duggal, a staff ICU physician and director for critical care research for the medical ICU at the Cleveland Clinic. “Anything that we do after that is really trying to minimize the damage associated with the viral infection.”

He said factors that affect treatment decisions in vaccinated people included whether someone has any underlying immunity as well as any comorbidities. Doctors say that while it remains unlikely that vaccinated people will end up in the hospital, those who do will likely be eligible for similar treatments. 

“Once you get hospitalized in breakthrough cases you will get all the usual therapies,” Dr. Duggal said. “Vaccination not only prevents the disease but also ameliorates the severity of disease.” He said some doctors in the U.S. have administered antibody treatments but it isn’t standard treatment and may not be appropriate since the virus infected the patient despite the presence of antibodies from the vaccines. 

What if I am immunocompromised and become infected?

Most of the hospitalized patients who were previously vaccinated are immunocompromised, according to doctors. Hospitalized patients who are immunocompromised are eligible to receive convalescent plasma, a highly concentrated solution of antibodies taken from recovered Covid-19 patients. There is limited data that suggests monoclonal antibody treatments will benefit the immunocompromised, even if they are vaccinated, said Dr. Duggal. 

—Joseph Walker contributed to this article.

Israeli experts analyze mRNA COVID vaccines long-term effects

Experts believe there will be no long-term side effects to the mRNA vaccines.

Authors: By MAAYAN JAFFE-HOFFMAN   AUGUST 30, 2021 22:34

As thousands of Israelis rush back to their health funds in search of a third COVID-19 vaccine shot and a Green Pass from isolation after traveling abroad, others are asking if another injection of messenger RNA is safe.The American Food and Drug Administration provided full approval of the Pfizer coronavirus vaccine last week, but noted in its press release that “information is not yet available about potential long-term health outcomes.”However, Tal Brosh, head of the Infectious Disease Unit at Samson Assuta Ashdod University Hospital, told The Jerusalem Post that while he cannot claim to know what is going to happen in 10 years, “there is no true reason to think there are any significant long-term effects” of the vaccine.He explained that there is no other vaccine that was evaluated for a decade before approval and that there is not an example of another vaccine – although no other vaccine is an mRNA vaccine – that has been linked to any significant long-term effects.“There is no evidence of something happening unless it happened in the first two hours, two weeks or two months,” said Michal Linial, a professor of biological chemistry at the Hebrew University of Jerusalem. “We do not know of any other examples in which the immune system decided to suddenly react to a vaccine that was given 15 years prior.”THERE ARE also few examples of people being nervous about taking a booster shot of an already approved vaccine.If a person were to get cut by rusted metal and go to a doctor, the health professional would probably tell that individual to get a tetanus booster shot. It is unlikely this person would ask the doctor if the booster was safe or if it could prevent her from getting pregnant or him from making babies.“This is the same thing,” Linial said. “I can understand in the beginning that this was a breakthrough and people were shocked, like it is some kind of satellite to the Moon and they don’t want to be the first on the satellite. But now we know: This is nothing like that.”Rather, more than two billion people worldwide have been inoculated against COVID-19 with more than five billion doses. Around 210 million Pfizer mRNA doses have been distributed in America, for example. In Israel, more than 8.5 million doses have been administered. While traditional vaccines generally put a weakened or inactivated germ into our bodies, according to the Centers for Disease Control and Prevention, mRNA vaccines “teach our cells how to make a protein – or even just a piece of a protein – that triggers an immune response inside our bodies. That immune response, which produces antibodies, is what protects us from getting infected if the real virus enters our bodies.”Brosh said that this does not mean that the vaccine changes people’s genetic code. Rather, he said the mRNA is more like a USB device that is inserted into a computer: It does not impact the hard drive of the computer but runs a certain program.“ Messenger RNA is a very fragile molecule, meaning it can be destroyed very easily,” Linial explained. “If you put mRNA on the table, for example, in a minute there will not be any mRNA left. This is as opposed to DNA, which is as stable as you get. ”She said that this fragility is true of the mRNA of any living thing, whether it belongs to a plant, bacteria,

WHILE THE Moderna and Pfizer vaccines are based on new technologies, they are asking our bodies to do something they do every day: cells synthesizing protein. Moderna and Pfizer are simply delivering a specific mRNA sequence to our cells. Once the mRNA is in the cell, human biology takes over. Ribosomes read the code and build the protein, and the cells express the protein in the body. This is one of the main reasons to believe there will be no long-term consequences to the vaccine, said Prof. Eyal Leshem, director of Sheba Medical Center’s Center for Travel Medicine and Tropical Diseases. While the Pfizer and Moderna vaccines are the first mRNA ones to ever be brought to market for human patients, Linial said she believes the reason that no mRNA vaccine has been developed until now is because there was just no need to move this fast on a vaccine until COVID-19 came along. In fact, scientists have been experimenting with mRNA for the better part of the last three decades. Leshem said mRNA vaccines for other diseases, including cancer, have been tested in humans for around 10 years and “no long-term effects were registered” in those trials – though he admitted that these trials generally included small numbers of participants. Individuals began receiving mRNA vaccines against COVID-19 as early as July of last year, and adverse effects have been closely tracked worldwide since then. In Israel, the first vaccines were administered on December 20, 2020.“There is more data on the adverse events of these vaccines than we have ever had on any other vaccine,” Brosh said, adding that no vaccine has ever been given to so many people so quickly. Most adverse events were simple “reactogenicity” – reactions that occur soon after vaccination and that are a physical manifestation of the inflammatory response. These can include fever, muscle pain, swelling at the site of injection or swelling of the lymph nodes, for example – all symptoms that can generally be treated with paracetamol or the like. THE VACCINE was linked to one “immune-mediated phenomenon,” said Brosh, and that is myocarditis – inflammation of the heart muscle – which was the predominant serious side effect in young male adults between the ages of 16 and 25. But even then, myocarditis was rare, generally mild, and those people who developed it fully recovered, he said. Moreover, unvaccinated people who contracted COVID-19 were four times more likely to develop myocarditis than vaccinated people were, according to a new study by Clalit Health Services together with Harvard University that was published last week in the New England Journal of Medicine. The study found that there were around 2.7 cases of myocarditis per 100,000 vaccinated people infected with the virus, compared with 11 cases per 100,000 unvaccinated people who were infected. In general, the study showed that individuals who take the Pfizer coronavirus vaccine may suffer from four out of up to 25 clinically relevant side effects: myocarditis, swelling of the lymph nodes, appendicitis and herpes zoster.In contrast, high rates of multiple serious adverse events were associated with coronavirus infection among unvaccinated patients, including a greatly increased risk of developing myocarditis, pericarditis, arrhythmias, heart attacks, strokes, pulmonary embolism, deep-vein thrombosis or acute kidney damage.“So, all together we know the vaccines are safe and effective. This holds true for the initial doses and probably also for the booster doses,” Leshem said. Linial said she believes that most future vaccines will be made of mRNA because “it is an easy, great technology – no question.” She also said that vaccination is the only way to beat this pandemic. “If people want to go back to their lives,” Linial said, “the population must be vaccinated.” 

Walking down the memory lane with SARS-CoV-2 B cells

Authors: Natalia T FreundMotti GerlicBen A Croker

The end of the coronavirus disease 2019 (COVID-19) pandemic is in sight. We have scientists to thank for that. However, while years of meticulous research by vaccinologists, molecular biologists and immunologists provided the framework for rapid deployment of vaccines, we are still learning what constitutes an effective lifelong immune response to pathogens. A more detailed understanding of human B-cell development and the nature of the antibody response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection or immunization may aid vaccine development for known pathogens and further reduce vaccine development times in the event of future pandemics.

Neutralizing antibodies are produced upon infection with SARS-CoV-2,12 but the transition to lifelong immunity awaits ongoing studies, and is of central importance to ending COVID-19. Immunological memory is the pillar by which vaccines offer education to our immune system to protect us from future exposure to pathogens, yet the nature and length of this memory vary. Some natural infections and vaccines provide a lifelong lesson to the immune system, thereby enabling it to “remember” pathogens and antigens for decades, while in other cases the immune system “forgets” the exposure, leading to a waning immune response over months to years. With the advent of vaccines against SARS-CoV-2, along with the emergence of variants of concern, understanding the nature and duration of protective immunity is key to SARS-CoV-2 eradication or, at least, minimalization of severe infections leading to hospitalization and death.

To study long-term immunity to SARS-CoV-2 infection and vaccination, Wang et al.3 have investigated memory B-cell responses to SARS-CoV-2 for a 12-month period in convalescent individuals, some of whom received a COVID-19 messenger RNA (mRNA) vaccine. SARS-CoV-2 convalescent individuals are advised to receive one dose, and in some countries two doses, of a COVID-19 vaccine to increase titers of SARS-CoV-2 antibodies to a level considered effective at virus neutralization. This recent study enables a longitudinal comparison of the natural B-cell response with infection, with and without a supplemental COVID-19 vaccine.

For More Information:

Swedish Professor Says 5 Shots Of COVID Vaccine May Be Necessary

While many people have bragged about being “fully vaccinated” after taking two COVID-19 jabs, a Swedish professor says that as many as five shots may be needed to combat falling immunity.

“We don’t know how long the vaccine protects against serious illness and death,” said Karolinska Institute Professor Matti Sällberg.

“This means that you pick the safe before the unsafe.”

Numerous European countries are planning a 3rd round of COVID “booster shots” in September, and the FDA also indicated that vaccinated individuals will be given another shot in the fall.

However, Sällberg suggests this probably won’t be enough and that “recurring shots” will be necessary.

“After receiving the second dose, the immune response slowly subsides. Within a year, many may have lost their protection. We do not know yet, but if you get a third dose, it will be activated again,” he said.

“Biology says that a fading immune response is not unlikely. Then it’s time for a third, fourth, maybe fifth dose”.

For More Information:

Review the safety of Covid-19 mRNA vaccines: a review

Authors: Pratibha Anand 1Vincent P Stahel 2


The novel coronavirus disease 2019 (COVID-19) has infected more than 100 million people globally within the first year of the pandemic. With a death toll surpassing 500,000 in the United States alone, containing the pandemic is predicated on achieving herd immunity on a global scale. This implies that at least 70-80 % of the population must achieve active immunity against the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), either as a result of a previous COVID-19 infection or by vaccination against SARS-CoV-2. In December 2020, the first two vaccines were approved by the FDA through emergency use authorization in the United States. These vaccines are based on the mRNA vaccine platform and were developed by Pfizer/BioNTech and Moderna. Published safety and efficacy trials reported high efficacy rates of 94-95 % after two interval doses, in conjunction with limited side effects and a low rate of adverse reactions. The rapid pace of vaccine development and the uncertainty of potential long-term adverse effects raised some level of hesitation against mRNA vaccines in the global community. A successful vaccination campaign is contingent on widespread access to the vaccine under appropriate storage conditions, deployment of a sufficient number of vaccinators, and the willingness of the population to be vaccinated. Thus, it is important to clarify the objective data related to vaccine safety, including known side effects and potential adverse reactions. The present review was designed to provide an update on the current state of science related to the safety and efficacy of SARS-CoV-2 mRNA vaccines.

For More Information:

Safety of SARS-CoV-2 vaccines: a systematic review and meta-analysis of randomized controlled trials

Authors: Musha ChenYue YuanYiguo ZhouZhaomin DengJin ZhaoFengling FengHuachun Zou & Caijun Sun 


Various modalities of vaccines against coronavirus disease 2019 (COVID-19), based on different platforms and immunization procedures, have been successively approved for marketing worldwide. A comprehensive review for clinical trials assessing the safety of COVID-19 vaccines is urgently needed to make an accurate judgment for mass vaccination.

A systematic review and meta-analysis was conducted to determine the safety of COVID-19 vaccine candidates in randomized controlled trials (RCTs). Data search was performed in PubMed, Embase, Cochrane library, Scopus, Web of Science, and MedRxiv. Included articles were limited to RCTs on COVID-19 vaccines. A total of 73,633 subjects from 14 articles were included to compare the risks of adverse events following immunization (AEFI) after vaccinating different COVID-19 vaccines. Pooled risk ratios (RR) of total AEFI for inactivated vaccine, viral-vectored vaccine, and mRNA vaccine were 1.34 [95% confidence interval (CI) 1.11–1.61, P < 0.001], 1.65 (95% CI 1.31–2.07, P < 0.001), and 2.01 (95% CI 1.78–2.26, P < 0.001), respectively. No significant differences on local and systemic AEFI were found between the first dose and second dose. In addition, people aged ≤ 55 years were at significantly higher risk of AEFI than people aged ≥ 56 years, with a pooled RR of 1.25 (95% CI 1.15–1.35, P < 0.001).


The safety and tolerance of current COVID-19 vaccine candidates are acceptable for mass vaccination, with inactivated COVID-19 vaccines candidates having the lowest reported AEFI. Long-term surveillance of vaccine safety is required, especially among elderly people with underlying medical conditions.

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The Thorny Problem Of COVID-19 Vaccines And Spike Proteins

Authors: W. Glen Pyle

Almost since the beginning of the COVID-19 pandemic, a piece of the SARS-CoV2 virus called the “spike protein” has drawn interest from researchers and healthcare professionals.

New research by Yuyang Lei and colleagues published in the journal Circulation Research sheds new light on how the spike protein might play a critical role in the widespread damage caused by SARS-CoV2, and offers insight into treating the complications of COVID-19.

Vaccine skeptics have seized on the study to cast doubt on the safety of vaccines. But a review of the study’s findings shows that the concerns raised by vaccine doubters are much ado about nothing.

The Study

The vascular endothelium is an important player in the illness and death associated with COVID-19. The endothelium is a system of cells that line and protect the inside of blood vessels. SARS-CoV2 injures the endothelium leading to blood clots, heart attack, pulmonary embolism, and stroke. Despite the established link between COVID-19 and these cardiovascular complications, the mechanism by which they develop is unknown.

Researchers from Jiaotong University; the University of California, San Diego; and the Salk Institute used a pseudovirus coated with spike protein to investigate the effects of the viral protein on endothelial cells. Pseudoviruses – which were first developed over 50 years ago – contain the outer shell of the virus, but they lack the viral genes needed to reproduce.

Hamsters treated with the spike protein coated pseudovirus showed lung damage similar to that seen in humans infected with SARS-CoV2. When researchers added pseudovirus to cultured endothelial cells they found that the mitochondria inside the cells were injured. Since mitochondria are responsible for providing energy to cells, their dysfunction can cause cell death.

When isolated pulmonary arteries were exposed to the spike protein carrying pseudovirus there was some disruption in the ability of the blood vessels to dilate. The decreased ability to expand blood vessels that serve the lungs could impair the ability of the body to take up oxygen from lungs that are damaged by the virus.

The novelty of this study was the discovery that the spike protein itself causes damage, and that the pathway triggered by the spike protein could explain the widespread cardiovascular complications that develop in COVID-19 patients.

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Efficacy and Safety of the mRNA-1273 SARS-CoV-2 Vaccine

Authors: Lindsey R. Baden, M.D., Hana M. El Sahly, M.D., Brandon Essink, M.D., Karen Kotloff, M.D., Sharon Frey, M.D., Rick Novak, M.D., David Diemert, M.D., Stephen A. Spector, M.D., Nadine Rouphael, M.D., C. Buddy Creech, M.D., John McGettigan, M.D., Shishir Khetan, M.D., et al., for the COVE Study Group*

Vaccines are needed to prevent coronavirus disease 2019 (Covid-19) and to protect persons who are at high risk for complications. The mRNA-1273 vaccine is a lipid nanoparticle–encapsulated mRNA-based vaccine that encodes the prefusion stabilized full-length spike protein of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes Covid-19.

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