Omicron significantly reduces Covid antibody protection in small study of Pfizer vaccine recipients

South African scientists say the omicron Covid variant significantly reduces antibodies generated by Pfizer and BioNTech’s vaccine, although people who have recovered from the virus and received a booster shot will likely have more protection from severe disease, according to a small preliminary study released Tuesday.

Prof. Alex Sigal with the Africa Health Research Institute and a team of scientists tested blood samples of 12 people who’d previously been vaccinated with the Pfizer/BioNTech vaccine, looking specifically at how well antibodies generated by the vaccine can neutralize the new variant – meaning block its ability to infect cells.

They found a 41-fold in drop in the ability of their antibodies to neutralize the omicron variant compared to the original virus, a dramatic reduction from its performance against the original ancestral strain as well as other variants, according to a preprint of the study that hasn’t yet been peer reviewed. Vaccine-induced antibodies dropped threefold in their ability to neutralize the earlier beta variant that previously dominated South Africa, suggesting omicron is much better at evading protection.

“The results we present here with Omicron show much more extensive escape” than the beta variant, researchers wrote. “Previous infection, followed by vaccination or booster is likely to increase the neutralization level and likely confer protection from severe disease in Omicron infection.”

The preprint study has not yet been peer reviewed and it tested 14 plasma samples from 12 vaccinated people, 6 of whom were previously infected. Scientists have been making their Covid research available prior to going through the extensive peer review process because of the urgency of the pandemic.

Pfizer CEO Albert Bourla said earlier Friday the company can develop a vaccine that specifically targets omicron by March 2022 if needed. Bourla said it will take a few weeks to get more definitive data on whether the current vaccines provide enough protection against the variant.

The Pfizer CEO had previously told CNBC that the protection provided by the company’s two-dose vaccine would likely decline some in the face of omicron.

The South African scientists also found the omicron attaches to the same receptor, known as ACE2, to infect human lung cells that previous variants used.

This is a developing story. Please check back for updates.