The U.S. Food and Drug Administration approved new COVID-19 shots for this fall, but only for a limited number of Americans.

Under the FDA's new guidance, the vaccine is approved for all adults 65 and older, but only for younger adults and kids with at least one medical condition that puts them at risk for severe illness from COVID.

Health Secretary Robert F. Kennedy, Jr., said on social media the new vaccines "are available for all patients who choose them after consulting with their doctors."

But many health experts say the change is in line with Kennedy's history of vaccine skepticism and will make it harder for some people to get a COVID shot.

"The FDA guidance will limit accessibility of the vaccine to individuals because it puts additional hurdles in place for otherwise healthy individuals to get the vaccine," said virologist Andy Pekosz.

Pekosz says the move could mean fewer people get the vaccine.

"This makes things much more complicated and when things get complicated, we see vaccine uptake go down."

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A CDC advisory panel that will meet in September still needs to vote to recommend the vaccine.

Kennedy fired all of the panel's members and appointed new ones earlier this year.

The panel's decision could determine if insurers will cover the COVID-19 vaccine for people outside of the recommended groups, according to Dr. Evan Nadler.

"If you're outside those age groups right now, it's unclear whether your insurance company will pay for that shot," Nadler said.

If insurers don't cover the vaccines, some patients could end up paying more than $140 out of pocket.