UW Med: Booster shots with existing vaccines offset some Omicron immune evasion tactics

Research in Veesler lab photo courtesy UW Med

Although Omicron subvariants of the SARS-CoV-2 pandemic coronavirus have evolved to evade antibody responses from the primary COVID-19 vaccine series, a new laboratory study suggests current vaccine boosters may elicit sufficient immune protection against severe Omicron-induced COVID-19 disease.

The project assessed a comprehensive panel of seven vaccines available in the United States or in other parts of the world, as well as immunity acquired through previous infection.

The findings are published today as an Early Release paper in Science because of their significance to the pandemic.Researchers in the Department of Biochemistry at the University of Washington School of Medicine in Seattle led the international study.

As the COVID-19 pandemic overstays its appearance on the world stage, genetic variants of the causative virus have emerged that are more transmissible, fitter, and more adept at avoiding infection-fighting strategies. 

The latest variant of concern, Omicron, has greatly diverged from the ancestral SARS-CoV-2 strain. It consists of several sublineages, including BA.5, which is predicted to soon dominate globally by replacing other variants. It is likely to become the most immune evasive SARS-CoV-2 variant to date. 

The results reported today in Science showed that the ability of Omicron BA.5 to bind with host cell receptors was more than 6 times stronger than the ancestral COVID-19 coronavirus.

The research team analyzed plasma samples from people who had been infected with COVID-19 before vaccines were available, as well as those who had completed only a primary vaccine series, and others who had been boosted with currently available vaccines. The vaccines assessed in this project were Moderna, Pfizer, Novavax, Jannsen, AstraZeneca, Sinopharm and Sputnik V.

The marked improvement in Omicron neutralizing activity in the plasma of boosted individuals highlights the importance of vaccine boosters in improving the potency of antibody responses against the Omicron strains.

--UW Med