For Omicron, Third Dose Of Covid Shot May Be Needed: Pfizer

Company researchers observed a 25-fold reduction in neutralizing antibody levels versus the variant, compared with the original strain of the virus, in people who got just two shots.

Pfizer and BioNTech SE said initial lab studies show a third dose of their Covid-19 vaccine may be needed to neutralize the omicron variant, results that will accelerate booster-shot drives around the world.

Company researchers observed a 25-fold reduction in neutralizing antibody levels versus the variant, compared with the original strain of the virus, in people who got just two shots. However, boosting with an additional shot of the vaccine raised antibodies 25-fold against omicron, giving a similar level of the protective proteins as observed against those earlier versions after the standard two doses, the vaccine partners said in a statement.

The lab findings indicate that two doses of the vaccine "may not be sufficient" to protect against infection with the omicron strain, the companies said in a release. Along with stimulating the booster push, that may increase the likelihood that an omicron-targeted shot may ultimately be required. Pfizer said this would be ready by March.

Uncertainty over vaccine efficacy against the new variant has fueled market volatility and prompted travel restrictions since omicron was identified in southern Africa last month. News of the study outcome helped buoy the U.S. stock market, with S&P 500 futures gaining 0.2%. Pfizer shares gained 0.5% in pre-market trading in New York, while BioNTech American depositary receipts rose 3%.