The FDA has updated labels on the top two COVID-19 vaccines to warn of a rare heart side effect, mostly seen in young men. Here's what to know.

"The committee has been plagued with persistent conflicts of interest and has become little more than a rubber stamp for any vaccine," he wrote in an op-ed for The Washington Post. "It has never recommended against a vaccine—even those later withdrawn for safety reasons."

U.S. health officials have expanded warnings about a rare heart side effect associated with the two leading COVID-19 vaccines.