Pfizer-BioNTech Booster Protects Against Omicron

Pfizer-BioNTech today reported the first, early results of studies examining how well their vaccine protects against the fast-spreading Omicron variant. The companies say that adding a booster to the two-dose vaccine regimen neutralizes the Omicron variant in lab studies.

In a press release, the companies noted that while two doses of their COVID-19 vaccine show decreased protection against Omicron, a booster dose significantly raises that protection. Blood samples from people vaccinated with a booster showed 25-fold higher levels of neutralizing antibodies against Omicron compared to blood serum from people immunized with just two doses. Essentially, the booster brought levels of these virus-fighting antibodies back to those seen after two doses against the original virus strain. More durable immune responses involving T cells were also higher against Omicron after a booster dose.

The findings, while preliminary, are encouraging for several reasons. First, they suggest that the current vaccine can continue to protect against the new variant. Researchers still don’t know how dangerous Omicron is—they continue to study how transmissible the variant is, as well as whether it causes more severe disease or evades the protection provided by vaccines. Results of those studies are expected soon. Until then, these findings hint that the existing vaccines can still thwart Omicron—as long as people receive a booster dose. The early results showed that two doses alone aren’t sufficient; after two doses, the immune system generated significantly lower levels of antibodies that could neutralize Omicron.

“The data very clearly indicate the value of a third dose,” BioNTech CEO and co-founder Uger Sahin said during a briefing discussing the results. “With the data now coming on the Omicron variant, it is very clear that our vaccine for the Omicron variant should be a three-dose vaccine. The best [strategy] now to ensure protection would be to get a booster shot, thereby improving levels of antibodies, [and] improving levels of T cells, which are correlated with better protection against the currently circulating Delta [variant] and which we believe will also translate to better protection against the Omicron variant.”

The findings do come with caveats. The studies were conducted not with live samples of the Omicron variant, but with a lab-made version of the virus. While it contained the same mutations, it’s still a proxy for the actual variant virus. Sahin said researchers plan to conduct the same studies with live Omicron samples in the coming weeks.

While it’s not clear exactly how the current vaccines continue to protect against new variants like Omicron, immunologists say that the quality of antibodies generated against viruses continues to evolve and improve with each exposure, or vaccine dose. That means that doses targeted against an earlier version of the virus could continue to provide protection against newer variants as well.

Still, Pfizer and BioNTech, as well as other vaccine makers, are developing a new vaccine designed to specifically target the Omicron variant. The mRNA technology behind Pfizer-BioNTech’s shot is flexible enough that scientists expect to have the new vaccine created in about six weeks, and tested a few months after that. BioNTech expects the first batches of an Omicron vaccine will be available by March, if it’s needed and authorized by regulators.

“The production process itself will stay the same,” Sierk Poetting, chief operating officer at BioNTech, said at the briefing about manufacturing a potential Omicron vaccine. “The only thing that will change is the … blueprint of the new variant. Apart from that, all the production steps, the mRNA, the lipid formulation, the fill and finish, will be exactly the same.”