Dr. Peter Marks, director of the Center for Biologics Evaluation and Research within the Food and Drug Administration, answers a question during a hearing of the Senate Committee on Health, Education, Labor and Pensions on the ongoing federal response to COVID-19 at the conference discuss U.S. Capitol in Washington, DC, May 11, 2021.

Greg Nash | Pool | Reuters

Covid-19 booster vaccinations could be required for fully vaccinated people within a year, the Food and Drug Administration’s supreme vaccine authority said Tuesday.

The current versions of the Pfizer-BioNTech and Moderna Covid-19 vaccines are highly effective in preventing Covid and also appear to protect against the variants circulating in the United States, said Dr. Peter Marks, director of the FDA Center for Biologics Evaluation and Research.

“So, hopefully, you know, it would be nice if it turned out it was going to be a year before someone needed 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 … that’s just something we need to find out when we go.”

Acting FDA Commissioner Dr. Janet Woodcock said U.S. regulators and scientists still don’t need to know how far immunity must drop in vaccinated people before they become susceptible to the virus.

“As for the variants, we just need to note that the immune response to these vaccines is currently being tested against all variants to see how strong it is against each of the variants. And we just hope that one variant doesn’t.” There are none that can evade our vaccines, “she said.

FDA officials’ comments come as drug manufacturers, and some scientists are now saying that people will likely need a booster shot of Covid-19 vaccines and possibly additional shots each year, just like they would with seasonal flu.

Pfizer and Moderna’s Covid-19 vaccines currently require two doses three to four weeks apart, while the Johnson & Johnson shot only requires one shot. All three vaccines have been shown to be highly effective against Covid, although company executives now expect the strong protection to wear off over time.

Ugur Sahin, CEO of BioNTech, told CNBC in a recent interview that researchers are seeing a decrease in antibody responses to the virus after eight months.

“If we give a boost, we could actually increase the antibody response beyond what we started with, and that could give us a real comfort of protection for at least 12 months, maybe 18 months,” said Sahin. “And that is really important at a time when all variants are coming.”

Should Americans need booster vaccinations, the US government would likely need to reach agreements with drug manufacturers to provide additional doses and make plans to distribute vaccines.

Last week, CDC Director Dr. Rochelle Walensky told CNBC that the US is planning the potential need for Covid-19 vaccine booster shots “just in case”.