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 updated warnings highlight a rare risk of heart inflammation in teen boys and young men, CBS News reported. The warning applies to males ages 16 to 25 and is based on new data from FDA safety monitoring and a 2023 study. This includes both Pfizer's Comirnaty and Moderna's Spikevax vaccines.