COVID-19: Omicron variant did not wipe out Delta, it could return

While the Delta virus wiped out the variants that preceded it, Omicron has not eliminated Delta, according to a new study from Israel’s Ben-Gurion University of the Negev.

Authors:  JUDY SIEGEL-ITZKOVICH Published: MAY 2, 2022 

Don’t throw away your unused face masks yet. COVID-19’s Omicron variants may burn themselves out in the next couple of months, and the Delta variant might re-emerge, researchers at Beersheba’s Ben-Gurion University of the Negev (BGU) suggest in a new scientific paper.

Their findings were just published in the peer-reviewed journal Science of the Total Environment under the title “Managing an evolving pandemic: Cryptic circulation of the Delta variant during the Omicron rise.”

The first new coronavirus to appear at the end of 2019 was Alpha, followed by Beta (first detected in South Africa); Gamma (first detected in Brazil); Delta (that revealed itself in India); and the more-infectious but milder Omicron, which has developed a variety of sub-variants and spread all over the world.

While the Delta variant wiped out the variants that preceded it, Omicron has not eliminated Delta, according to Prof. Ariel Kushmaro and Dr. Karin Yaniv, who just received her doctorate in the field.

The lab team has developed sensitive arrays that can differentiate variants from each other in wastewater, which continues to give indications of where the coronavirus is active, even when PCR and rapid testing of people declines.

Kushmaro, who earned his advance degrees in molecular microbiology and biotechnology at Tel Aviv University, trained as postdoctoral fellow at the Hebrew University and at Harvard. He arrived at BGU 21 years ago and established a lab at the School of Sustainability and Climate Change and the Goldstein-Goren Department of Biotechnology Engineering.

The lab specializes in wastewater microbiology, marine microbial ecology and antimicrobial activity of varies microorganisms as well as biological treatment of industrial wastewater.

His team monitored Beersheba’s sewage from December 2021 to January 2022 and noticed this disturbing interaction between the Omicron and Delta variants.

They also built a model with Granek that predicts that Omicron is burning itself out while Delta is just waiting to pounce on the population again.

“SARS-CoV-2 continued circulation results in mutations and the emergence of various variants. Until now, whenever a new, dominant, variant appeared, it overpowered its predecessor after a short parallel period,” they wrote.

“Despite vaccination efforts in Israel, with a large portion of the population being vaccinated between the first to fourth dose of vaccine and despite high infection rates by previous variants, the Omicron variant had now rooted itself in Israel.”

The latest variant of concern, Omicron, is spreading swiftly around the world with record morbidity reports, wrote the authors. “Unlike the Delta variant, previously considered to be the main variant of concern in most countries, including Israel, the dynamics of the Omicron variant showed different characteristics.”

If their prediction comes to pass, its circulation may result in the reemergence of a Delta morbidity wave or in the possible generation of a new threatening variant, they wrote.

With the expected significant decline in morbidity from all the recovered Omicron cases, the Israeli government and the Health Ministry have eliminated most restrictions. “In the meantime, the Delta, which is still circulating in a population with waning immunity and under fewer restrictions, may re-emerge in larger numbers or even produce a new, different variant to generate infections in Israel.”

In any case, the team recommended wastewater-based epidemiology as a “convenient and representative tool for pandemic containment.

“Of course, there are a lot of factors involved, but our model indicates there could be another outbreak of Delta or another coronavirus variant this summer,” warned Kushmaro, who was assisted by Dr. Eden Ozer and Marilou Shagan at BGU and Dr. Yossi Paitan from Ilex Labs. 

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