The CDC vaccine advisory committee, called ACIP, voted 8-3 to narrow the recommendations. One person abstained from voting due to a conflict of interest. Another vote on dropping a longstanding recommendation to give all newborns a hepatitis B vaccination at birth was delayed until Friday.

The group was chosen by Health Secretary Robert F. Kennedy Jr. amid controversy. It's changed guidance for for measles, mumps, rubella and chickenpox shots and deferred proposed changes to hepatitis B.

Under the CDC's current list of high-risk conditions, "almost everyone who wanted to receive a vaccine could," William Schaffner, MD, of Vanderbilt University in Nashville, Tennessee, told MedPage Today. "Whether that will be acceptable going forward is uncertain."

Preexisting health conditions mean a majority of adults qualify for a COVID shot under current FDA guidelines — but there are still roadblocks to getting it.