A health care worker administers the Pfizer COVID-19 vaccine to a middle school teacher in Medina, Ohio, on February 4. File Photo by Aaron Josefczyk/UPI | License Photo
Jan. 24 (UPI) -- Antibodies capable of countering the Omicron variant of the COVID-19 virus are still present in the body four months after a booster shot of the Pfizer-BioNTech vaccine, researchers have reported.
Data gathered by scientists working for the vaccine maker and the University of Texas Medical Branch provided what they called "the first glimpse of the neutralization durability against Omicron" in a preliminary report published Saturday.
The results, which have not yet been peer-reviewed, demonstrated support for a three-dose vaccine strategy and indicated that a fourth shot may not be needed in the near future.
The data confirms previous results demonstrating that "serum antibodies induced by [the Pfizer vaccine] neutralize the SARS-CoV-2 Omicron variant after immunization with three doses," while antibody response for those with only two doses "may not be sufficient to protect against infection with the new variant," the pharma companies announced.
Even with just two doses, however, the antibody response against Omicron is still robust enough to prevent severe disease, they added.
"This is very, very new for the field," University of Texas microbiologist and lead study author Pei-Yong Shi told The Washington Post. "That really shows that at least up to four months, post-dose three, there is still substantial neutralizing activity against Omicron."
Because antibody counts begin to wane several months after an initial vaccination, concerns quickly mounted over whether the Omicron variant could evade the Pfizer-BioNTech vaccine. Earlier studies showed little antibody response to Omicron in subjects who had not received a third-dose booster.
But, like a similar study on the Moderna vaccine in December, researchers detected a significant antibody uptick following a booster shot.
"First time we've seen Omicron nAbs this far out (4 months) and they're unexpectedly still quite high, which is great," tweeted Eric Topol, a professor of molecular medicine at the Scripps Research Institute.
Pfizer and BioNTech said that in the coming months they will be evaluating how an additional dose of both its current COVID-19 formulation and a new vaccine specifically tailored for the Omicron variant perform in a clinical setting.
The companies say they expect to produce 4 billion doses of their vaccine this year -- a level that is not expected to change even if a new, Omicron-specific formula is required.
The study comes after the Centers for Disease Control and Prevention reported last week that current COVID-19 vaccines were less effective at preventing against infection after Omicron emerged in November, but still lowered the risk for serious illness among those who are fully vaccinated, as well as those who have received booster doses.