In just two weeks, the Omicron variant has spread to more than 40 countries, including the U.S. Virus experts and health officials have expressed concerns about the new variant’s transmissibility and its effect on vaccine protection: Omicron has a number of mutations on the spike protein that could potentially spell trouble for existing vaccines, which have been designed to target this protein. Major vaccine manufacturers like Pfizer and Moderna have already announced plans for Omicron-specific boosters, but they’ve said these could take months to develop—and that might be too late. Now, researchers are trying to understand how existing boosters might help protect against this new iteration of the virus.
During a Dec. 8 interview with MSNBC’s Andrea Mitchell, top White House COVID adviser Anthony Fauci, MD, discussed how he expects the current vaccines to work against Omicron. According to Fauci, one of the major concerns when this new variant popped up was how protection from existing vaccines would respond to it.
But a new report from Pfizer has inspired some optimism. Pfizer and BioNTech revealed the results of lab experiments testing their vaccine’s effectiveness against Omicron in a Dec. 8 announcement. According to the manufacturers, blood samples taken from patients one month after they received a third booster shot showed an antibody response that was similar in strength to what the initial two shots showed against previous variants.
Ugur Sahin, MD, the CEO of BioNTech, said that it was clear that Pfizer’s booster could still “offer a sufficient level of protection” against Omicron. Meanwhile, those who got a Moderna booster are still waiting for that data, but according to Fauci, Pfizer’s report can likely help us determine how Moderna’s booster will fare against the new variant.
“Thus far, virtually everything we said about effectiveness of the Pfizer can be applied to Moderna. They’re really quite comparable,” Fauci told Mitchell. “I would really be very surprised if we did not see the same sort of an effect with Moderna as is now being reported with Pfizer.”
But Fauci also warned against taking the Pfizer report at face value, because it is only laboratory data and not clinical data. “Laboratory data projects what you might see clinically,” he explained. “So, obviously, the proof of the pudding is going to be what the clinical effect is, but the laboratory effect often projects accurately what you would see clinically.”
If Pfizer’s laboratory data does prove accurate, the infectious disease expert said he is optimistic about the level of protection those who get a booster are going to have against this new variant in real-world settings. “When you get a booster, you dramatically increase the level of projected protection by about 25-fold,” Fauci said. “This means people who get boosted after their two dose mRNA should really do quite well [against Omicron]. That’s what we’re projecting we will see clinically.”
According to Pfizer and BioNTech’s report, their results found blood samples that showed a 25-fold reduction in antibodies for those with only two doses, which the companies said “may not be sufficient to protect against infection” from Omicron. But Fauci noted that even if you only have two doses, the laboratory data projects that you will still likely have protection against severe disease, hospitalization, and death from the new variant.
“The bottom line lesson in all of this and the message is, for those who are unvaccinated, please get vaccinated,” he said. “And for those who are fully vaccinated, get that booster shot because that makes a big difference.”