Covid-19 booster shots could be needed for fully vaccinated people within a year, the Food and Drug Administration's top vaccine regulator said Tuesday.
The current versions of the Pfizer-BioNTech and Moderna Covid-19 vaccines are highly effective at preventing Covid and also appear to protect against the variants circulating in the United States, said Dr. Peter Marks, director of the FDA's Center for Biologics Evaluation and Research.
"So, hopefully, you know, it would be nice if it'll turn out that it'll be a year before anyone might need a booster," Marks said during a virtual press conference on the Covid-19 vaccines with high school and middle school journalists.
"But we still don't know," he added. "It could be more, it could be a little less but ... this is just something we're gonna have to figure out as we go."
Acting FDA Commissioner Dr. Janet Woodcock said U.S. regulators and scientists still need don't know how far immunity levels need to drop in vaccinated individuals before it leaves them vulnerable to the virus.
"As far as variants go, we're just going to have to determine that currently the immune response to these vaccines is being tested against all the variants to see how strong it is against each of the variants. And we just hope a variant doesn't arise that can elude our vaccines," she said.
The FDA officials' comments come as drugmakers and some scientists now say people will likely need a booster shot of the Covid-19 vaccines and possibly additional shots each year, just like for the seasonal flu.
Pfizer's and Moderna's Covid-19 vaccines currently require two doses given three to four weeks apart, while Johnson & Johnson's shot requires just one jab. All three vaccines have been shown to be highly effective against Covid, though company executives now say they expect that strong protection to wane over time.
BioNTech CEO Ugur Sahin told CNBC in a recent interview that researchers are seeing a decline in antibody responses against the virus after eight months.
"If we provide a boost we could really amplify the antibody response even above the levels that we had at the beginning and that could give us real comfort for protection for at least 12 months, maybe 18 months," Sahin said. "And this is really important in a time where all the variants are coming in."
Should Americans require booster shots, the U.S. government would likely need to make arrangements with the drugmakers to supply additional doses and make plans for vaccine distribution.
Last week, CDC Director Dr. Rochelle Walensky told CNBC that the U.S. is planning for the potential need for Covid-19 vaccine booster shots "just in case."