Senator Bill Cassidy from Louisiana has voiced his disapproval on Monday regarding the selections made by Health and Human Services Secretary, Robert F. Kennedy Jr., for a crucial federal vaccine advisory committee. Cassidy has urged for the postponement of the committee’s upcoming meeting until it includes more members with the necessary expertise.

This month, Kennedy unexpectedly dismissed all 17 existing members of the Centers for Disease Control and Prevention’s Advisory Committee on Immunization Practices and appointed eight new individuals, among whom are recognized vaccine skeptics. The newly formed group is expected to hold its first meeting on Wednesday and Thursday.

Cassidy, who holds a medical degree and chairs the Health, Education, Labor and Pensions Committee, had a significant role in Kennedy’s confirmation process. He supported Kennedy’s appointment after Kennedy assured him, among other promises, that there would be no alterations to ACIP, an influential panel responsible for vaccine recommendations and guiding the childhood vaccination schedule.

Cassidy expressed concerns Monday on X about the newly appointed members.

“Although the appointees to ACIP have scientific credentials, many do not have significant experience studying microbiology, epidemiology or immunology. In particular, some lack experience studying new technologies such as mRNA vaccines, and may even have a preconceived bias against them,” Cassidy wrote.

“Wednesday’s meeting should not proceed with a relatively small panel, and no CDC Director in place to approve the panel’s recommendations. The meeting should be delayed until the panel is fully staffed with more robust and balanced representation—as required by law—including those with more direct relevant expertise,” he continued.

Susan Monarez, President Donald Trump’s pick for CDC director, will have her Senate confirmation hearing Wednesday. Without a CDC director, Kennedy has signed off on some ACIP recommendations. And last month, without input from ACIP, he announced that the Covid vaccine would no longer be recommended for healthy children and pregnant women.

The Department of Health and Human Services, which oversees the CDC, did not immediately respond to a request for comment. HHS spokesperson Andrew Nixon previously defended Kennedy’s ACIP picks, saying in a statement that the new panel “includes highly credentialed scientists, leading public-health experts, and some of America’s most accomplished physicians. All of these individuals are committed to evidence-based medicine, gold-standard science, and common sense.”

A draft agenda for this week’s ACIP meeting includes a discussion and a vote on flu vaccines that contain thimerosal, a form of mercury that had been used as a preservative in some vaccines. Kennedy has long espoused the debunked claim that there is a link between thimerosal and autism.

Since 2001, nearly all vaccines made in the United States contain no thimerosal or only trace amounts. Only multi-dose flu shot vials still contain the preservative. Most flu shots now come in single-shot packaging.