Kennedy has been most vocal about the FDA, an agency that oversees nearly $3 trillion in medicines, food and tobacco products.

NBC News' Berkeley Lovelace Jr. reports that some officials in the Food and Drug Administration are grappling with how to handle their positions if Robert F. Kennedy Jr. takes over as Health and Human Services secretary.

Staff turnover is typical when a new administration comes in, and a significant number of FDA employees similarly considered leaving before President-elect Donald Trump’s first term in office, said one former and one current official.

Food and Drug Administration commissioner Robert Califf said he was “disappointed” with the presidential election result and is uncertain about the agency’s future under Donald Trump. “I’m biased, but I feel like the FDA is at peak performance right now and we’ll just see what happens as the new team comes in,

Shares in global vaccine makers and drugmakers fell on Friday after U.S. President-elect Donald Trump picked Robert F. Kennedy Jr., who has previously spread misinformation on vaccines, to lead the Department of Health and Human Services (HHS).

Pfizer's stock dropped 4.3 percent while Moderna's fell 3.1 percent and Novavax saw a 2.8 percent dip in its stock Friday morning.