The head of the U.S. Food and Drug Administration (FDA) reiterated Tuesday that the agency is applying a more skeptical approach to this year’s round of COVID-19 vaccine boosters.

Companies applying for approval of COVID boosters are being encouraged to use “gold standard science,” including full-fledged clinical trials involving healthy people, FDA Commissioner Dr. Marty Makary said today at the American Hospital Association's annual meeting in Washington, D.C.

That approach could mean no COVID boosters will be approved in time for next winter’s respiratory disease season, Makary has warned in earlier interviews.

“We need some better data. We can't just extrapolate from a clinical trial from four or five years ago,” he said at the conference. “Americans have a very low uptake and a very low confidence of the COVID boosters right now.”

For example, 85% of health care workers did not get the last COVID booster, Makary noted.

“It's reasonable to say we'd like to see a clinical trial rather than just some antibodies that spike after you give [the vaccine],” he said. “You can make antibodies spike to anything. That doesn't tell us that it actually has a clinical benefit. Americans want to know do we really, is there really a clinical benefit in healthy subjects.”

The FDA also is considering whether COVID boosters should be given primarily to high-risk groups, as opposed to general coverage, Makary added.

“Should we really be putting the full weight of the government to urge vaccination against COVID for a healthy, thin 12-year-old girl with her seventh COVID booster right now today in America?” Makary said. “I don't think so.”

The commissioner also downplayed the impact that layoffs ordered by the Trump Administration might have on the FDA’s effectiveness.

“There's a lot of people with impressive sounding titles, but that may not necessarily mean that they are working towards the core mission of the agency, which is to deliver more cures, diagnostics, therapeutics and healthy foods,” Makary said. “We're committed to public safety, which was why none of the cuts that were made included scientific reviewers or inspectors.”

The FDA has doubled its staff since 2007, Makary said, increasing from 9,500 employees to 19,000 employees just a few months ago.

Under the Trump Administration, there’s been a 12% reduction in the work force, Makary said, noting that’s a lower level of staffing cuts than those ordered under President Bill Clinton for the U.S. Department of Health and Human Services.

“We need a lean FDA that's efficient, not a bloated FDA that is inefficient and slows down our approvals and inspections,” Makary said.