The FDA picked the LP.8.1 Covid strain for the fall vaccines, fueling concerns that the shots may be limited to only the most at-risk Americans this fall.

The Food and Drug Administration says it has decided to continue approving COVID-19 vaccine updates for seniors and others at higher risk of severe disease, but will require vaccine makers to conduct major new clinical trials before approving them for wider use.

The notice came shortly after an advisory panel meeting at which members debated the pros and cons of asking manufacturers to update their vaccines.