Scott Gottlieb, who served as commissioner of the Food and Drug Administration (FDA) during President-elect Trump’s first term, expressed concerns with the pick of Robert F. Kennedy Jr. to lead the Department of Health and Human Services (HHS) due to his anti-vaccine advocacy.

“I think if RFK follows through on his intentions, and I believe he will, and I believe he can, it will cost lives in this country,” he said during a Friday appearance on CNBC’s “Squawk Box.”

“You’re going to see measles, mumps and rubella vaccination rates go down, and like I said, if we lose another 5 percent [of vaccinations], which could happen in the next year or two, we will see large measles outbreaks,” he continued.

Many are worried Kennedy, who would need to be confirmed by the Senate to become HHS secretary, will amplify vaccine hesitancy for children despite his promise not to take away vaccines.

Gottlieb said he doesn’t think Trump wants to see a “resurgence” in infectious diseases, such as measles, polio and whopping cough. But he noted the nation’s doctors aren’t prepared to provide patients with diagnoses for diseases that have been largely absent for several decades, which could rise if vaccine rates drop.

The doctor who resigned from the FDA in 2019 before joining Pfizer’s board of directors, warned that Kennedy could increase the spread of infectious diseases with the “stroke of a pen.”

Still, he emphasized that some in the GOP may not be on board with Kennedy’s politics, which could halt his confirmation to lead the health department.

“I think there is skepticism in the Republican caucus — more than I think the press is reporting right now,” he said, noting that lawmakers who are against abortion rights dislike Kennedy’s opposing stance and that senators from agricultural states are concerned about his policy proposals’ impact on food prices.

Gottlieb praised Trump’s selection of Mehmet Oz to lead the Centers for Medicare and Medicaid Services, and Martin Makary to head the FDA. He noted Oz could be a “transformative” pick to lead the agency and highlighted his confidence in Makary.

“There are some qualified, very capable picks,” he continued.

The Hill reached out to the Trump team for comment.