Kennedy has been criticized for making false medical claims. He has also vowed to purge the U.S. Food and Drug Administration.

Vaccine stocks have struggled since RFK Jr.'s appointment to health secretary, with Moderna and Pfizer seeing the deepest losses.

President-elect Donald Trump said he’s tapping Robert F. Kennedy Jr. to run the Department of Health and Human Services, a move that would elevate a prominent vaccine skeptic and pharmaceutical industry critic to a top role on federal health policy.