Pfizer said Wednesday that a booster of its COVID-19 vaccine may offer important protection against the new omicron variant even though the initial two doses appear significantly less effective.
Pfizer and its partner BioNTech said that while two doses may not be strong enough to prevent infection, lab tests showed a booster increased by 25-fold people’s levels of antibodies capable of fighting off omicron.
For people who haven’t yet had a booster, the companies said two doses still should prevent severe disease or death.
Health authorities in the U.S. and other countries have urged eligible people to get a third dose even before these results.
“Go and get your third boost as soon as possible,” Dr. Mikael Dolsten, Pfizer’s chief scientific officer, told The Associated Press. “This is comforting and a very positive message that we now have a plan that will induce immunity that is likely to protect from infection, symptomatic illness and severe disease from now across the entire winter season.”
President Joe Biden said the Pfizer booster finding is “very encouraging” although he cautioned, “that’s the lab report. There’s more studies going on.”
Pfizer and BioNTech tested blood samples taken a month after a booster and found people harbored levels of omicron-neutralizing antibodies that were similar to amounts proven protective against earlier variants after two doses. For the lab tests, researchers grew samples of so-called “pseudoviruses” that hold the worrisome new mutations.
Scientists don’t yet know how big a threat the omicron variant really is. Currently the extra-contagious delta variant is responsible for most of the COVID-19 cases in the U.S. and other countries.
But the omicron variant, discovered late last month, carries an unusually large number of mutations and scientists are racing to learn how easily it spreads, whether it causes illness that is more serious or milder than other coronavirus types — and how much it might evade the protection of prior vaccinations.
Pfizer’s findings, announced in a press release, are preliminary and haven’t yet undergone scientific review. But they’re the first from a vaccine maker examining whether the booster doses that health authorities are urging people to get may indeed make a key difference.