What We Know About Omicron and COVID Vaccines As Pfizer Says Booster Neutralizes Variant

The Omicron variant poses significant—but incomplete—resistance to existing COVID vaccines, studies show, and boosters may help greatly.

Over recent days laboratory studies have been published providing some early data on how well the Pfizer vaccine performs against Omicron.

Earlier today, Pfizer and BioNTech released preliminary laboratory study data suggesting that three doses of the Pfizer vaccine appeared to increase neutralizing activity against Omicron 25-fold compared to two doses.

In a joint press release, the companies said that the study involved looking at blood samples from people who had received either two or three Pfizer vaccine shots, but did not disclose the sample size or how many people the samples were taken from. Newsweek has contacted Pfizer and BioNTech for comment.

According to the companies, the study "[demonstrated] that serum antibodies induced by the Pfizer-BioNTech COVID-19 Vaccine (BNT162b2) neutralize the SARS-CoV-2 Omicron variant after three doses" at a level comparable to "two doses against wild-type and other variants that emerged before Omicron."

The companies added they were still planning to have an Omicron-specific vaccine ready for March if needed.

In addition, another study released earlier this week, led by Alex Sigal at the Africa Health Research Institute, looked at what happened when the Omicron variant virus was exposed to the blood of 12 different people who had all received a Pfizer vaccine series. Six of those people had previously had COVID.

The study found there was a 41-fold reduction in neutralization against Omicron compared to an earlier form of SARS-CoV-2, a substantial decrease—though it does not mean the vaccine is 41 times less effective.

The study also found the neutralization escape was not complete and that five of the participants, all of whom had been previously infected, showed "relatively high" levels of neutralization against Omicron.

It concluded that previous infection, followed by a vaccination or booster, will "likely confer protection from severe disease in Omicron infection."

On Twitter, Sigal said the study results were "better than I expected of Omicron" and suggested existing methods to deal with COVID would help control the variant.

At the same time, the study is early and small and future ones should include samples from people who had received booster shots, tweeted Muge Cevik, clinical lecturer in infectious diseases and medical virology at the U.K.'s University of St. Andrews. In short, more data is needed to paint a definitive picture of Omicron.

Both Johnson & Johnson and Moderna have also announced their vaccines will be tested against the Omicron variant.

At the moment these studies into Omicron are very early and scientists will be testing how the virus responds to vaccines, as well as how fast it spreads and what sort of illness it causes, for several more weeks.

COVID vaccine
A COVID vaccine shot is prepared at the Centro de Estudios Superiores Navales (CENSIS) in Mexico City on December 7, 2021. Scientists are working to find out how effective vaccines are against the Omicron variant. Pedro Pardo/AFP/Getty