If You Got Pfizer, This Is How Protected You Are Against Severe Omicron
A South African study shows how much the latest variant drops the vaccine's effectiveness.
In the short time since it was first identified, the Omicron variant has created concern among experts as it's managed to spread to dozens of countries. Officials in both the U.S. and Europe announced they expect the latest version of the virus to eclipse the Delta variant in dominance in the coming weeks. And now, new research shows that Omicron might affect how much the Pfizer vaccine protects someone from severe disease from the virus.
The latest insight comes from a study conducted by Discovery Health, which is the largest private health insurer in South Africa. Data collected from more than 211,000 people who tested positive for the virus shows that the 90 percent effectiveness provided by two shots of the Pfizer vaccine against symptomatic infection drops to 33 percent against Omicron, USA Today reports. Protection against severe COVID is still around 70 percent in patients who are fully vaccinated, however, even though this number began to diminish in patients above age 60 and even more so above age 70.
Some experts reacted with initial concerns over the findings. "This is the first time we've had any data on that," Eric Topol, MD, vice president for research at Scripps Research in La Jolla, California, and a national expert on the use of data in medical research, told USA Today. "Seventy percent is definitely a dropdown. It isn't great. It was 95 percent effective severe disease when it was Delta variant and then about 85 percent after six months of waning."
But in a series of tweets posted on Dec. 14, Topol pointed out research from the U.K. Health Security Agency that found a booster of the vaccine restored protection against symptomatic breakthrough infections to 75 percent against the latest version of the virus. Ultimately, he concluded the current data was missing insight on how effective a third shot of the Pfizer vaccine might be against severe outcomes with the virus. "We still need to know how the booster does [versus] Omicron for prevention of hospitalization and death, and how long it lasts," he wrote.
The latest findings come just days after Pfizer and BioNTech revealed the results of lab experiments testing their vaccine's effectiveness against the latest variant on Dec. 8. The company's study 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—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.
During an interview with NBC's Today on Dec. 8, 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."
While questions may remain, scientists still found some good news in the latest research. "What is encouraging at this stage is a flatter trajectory of hospital admissions indicating likely lower severity of this wave," Ryan Noach, MD, CEO of Discovery Health, said during a news briefing.
However, Noach tempered the positive side of the findings by pointing out another potentially serious side to the study's results that hinted the latest variant could still put a strain on healthcare systems. "The Omicron-driven fourth [wave] has a significantly steeper trajectory of new infections relative to prior waves," he said in a statement. "National data show an exponential increase in both new infections and test positivity rates during the first three weeks of this wave, indicating a highly transmissible variant with rapid community spread of infection."