Effects of a BioNTech/Pfizer Booster after the Sinovac Vaccine Studied

New variants of SARS-CoV-2 keep emerging during the pandemic. The omicron variant has been found concerning due to its high transmissibility and potential immune escape properties. Understanding how different vaccination and booster protocols affect the protection against omicron is important.

Carolina Lucas, Yale University School of Medicine, New Haven, CT, USA, Akiko Iwasaki, Yale University School of Medicine, Yale School of Public Health, New Haven, CT, USA, and Howard Hughes Medical Institute, Chevy Chase, MD, USA, and colleagues have studied the effects of a booster shot with the mRNA-based BioNTech/Pfizer vaccine (BNT162b2) after an initial immunization with CoronaVac. CoronaVac (the Sinovac COVID-19 vaccine) is an inactivated vaccine used in many countries, mostly in Asia, South and Central America, and Eastern Europe. The team evaluated the protection against the delta and omicron variants of SARS-CoV-2, using plasma samples from 101 study participants who had received a BioNTech/Pfizer booster at least four weeks after a second dose of CoronaVac.

The researchers found that 28 days after the booster shot, there was a sixfold increase in neutralization activity against the delta variant. The antibody levels were similar to those in a control group that had received two doses of an mRNA vaccine. Participants who had received two doses of CoronaVac had no detectable neutralizing antibodies to omicron. 80 % of these participants had antibodies after the booster. However, the protection from omicron overall was significantly lower than that from the delta variant or the ancestral virus. According to the team, this indicates a greater risk of breakthrough infection, while the likelihood of severe disease still needs to be evaluated.

Neutralizing antibodies against the SARS-CoV-2 Delta and Omicron variants following heterologous CoronaVac plus BNT162b2 booster vaccination,
Eddy Pérez-Then, Carolina Lucas, Valter Silva Monteiro, Marija Miric, Vivian Brache, Leila Cochon, Chantal B. F. Vogels, Amyn A. Malik, Elena De la Cruz, Aidelis Jorge, Margarita De los Santos, Patricia Leon, Mallery I. Breban, Kendall Billig, Inci Yildirim, Claire Pearson, Randy Downing, Emily Gagnon, Anthony Muyombwe, Jafar Razeq, Melissa Campbell, Albert I. Ko, Saad B. Omer, Nathan D. Grubaugh, Sten H. Vermund, Akiko Iwasaki,
Nat. Med. 2022.
https://doi.org/10.1038/s41591-022-01705-6

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