If You Got Pfizer, This Is How Your Antibodies React to Omicron, Studies Say
New research shows how the COVID vaccine can help protect against the latest variant.
The Omicron variant may only have been recently discovered, but it's already pressing scientists to search for answers on how much of a threat it could be. Many health experts fear that the latest viral offshoot might be more transmissible than the currently dominant Delta variant, while others are concerned that it could make current vaccines significantly less effective. But now, the breakneck pace of research is beginning to provide some answers about Omicron, including how your antibodies might react to the variant if you received the Pfizer vaccine.
In an announcement on Dec. 8, Pfizer and BioNTech revealed the results of lab experiments testing their vaccine's effectiveness against the latest variant. Results found that blood samples taken from patients who had only received the initial two doses saw a 25-fold reduction in antibodies, which the companies said "may not be sufficient to protect against infection" from Omicron. However, samples taken from patients one month after receiving a booster shot of the vaccine saw an antibody response that was similar in strength to levels recorded against previous variants after the initial two shots, The New York Times reports.
The tests also suggest that T cells—which are a critical part of the immune response—did not appear to be affected by the high number of mutations observed on the Omicron variant's spike proteins. According to the companies, this could mean that "vaccinated individuals may still be protected against severe forms of the disease" even if they've only received their initial shots.
Additionally, the findings appear to show that boosters could be essential in protecting against the latest viral offshoot. "Our preliminary, first data set indicate that a third dose could still offer a sufficient level of protection from disease of any severity caused by the Omicron variant," Ugur Sahin, MD, the chief executive officer of BioNTech, said in a statement.
During an interview with NBC's Today shortly after the study's release, Pfizer CEO Albert Bourla said that a vaccine booster "dramatically" improved the protection it provided against the latest variant. "To make it clear for your audience, three doses against Omicron are almost equivalent to the [two] doses effectiveness we had against … the original variant," he said. "You may need to go get the third booster faster, and that's something that the health authorities should consider very carefully and make their recommendations," he added, "but clearly having two doses compared to nothing protects you way better than having nothing."
Another report posted on Dec. 7 by scientists in South Africa also appears to support the findings of the Pfizer study. In lab experiments, researchers collected samples of antibodies from six people who had received the Pfizer vaccine without ever having been infected with COVID-19 and six people who had gotten COVID prior to being vaccinated. These antibodies were then analyzed against the variant, The New York Times reports. It was found that antibodies from all patients performed worse against Omicron, dropping to one-fortieth of the potency seen against previous variants in those who had only been vaccinated.
But results also found that five out of six patients who had been infected before vaccination saw a much stronger response, which researchers say is likely due to the more robust antibody response previously infected patients typically generate after receiving their shots. Researchers said this might mean that getting a third dose could make the vaccine more effective thanks to the increased antibodies. "My impression is if you get a booster, you are protected, especially against severe disease," Alex Sigal, PhD, the study's lead researcher and a virologist at the Africa Health Research Institute in Durban, South Africa, told CNN.
Even though the results suggest that breakthrough cases are a distinct possibility with Omicron, they also indicate that current vaccines can help prevent severe illness, hospitalization, and death. "While I think there's going to be a lot of infection, I'm not sure this is going to translate into systems collapsing," Sigal speculated. "My guess is that it'll be under control."
Other experts are also predicting that a third dose will help the fight against Omicron. "I expect boosters to restore better levels of protection," Kristian Andersen, PhD, an infectious disease researcher at the Scripps Research Institute in La Jolla, California, who was not involved in the South African study, told The New York Times. "And, importantly, early clinical data from South Africa suggest that immunity—whether from vaccines or prior infections—is still effective in preventing the more severe forms of COVID-19."
In the days leading up to the release of the studies, some health officials had already begun giving relatively optimistic outlooks on the latest variant. During a Dec. 3 interview on ABC's Good Morning America, CDC Director Rochelle Walensky, MD, discussed the Omicron cases that the U.S. is currently seeing across nearly 20 states. Overall, she said that vaccinated people are mostly experiencing less severe illness when they get infected with the variant.
"What we can say, based on what these cases are showing, some have mild disease, some may have more severe disease, many of them are vaccinated, and what we're seeing now is that many of the people with mild disease were the vaccinated people," Walensky explained.