Republican Sen. Bill Cassidy of Louisiana expressed concern that new members of the Centers for Disease Control and Prevention's Advisory Committee on Immunization Practices lack the expertise to be on such a panel.

The ACIP provides government regulators with guidance on changes to vaccines. Members generally weigh in before the cold and flu season to suggest updates to annual flu and COVID-19 shots.

Earlier this month, Health and Human Services Secretary Robert F. Kennedy Jr. removed all 17 members of the committee.

"Today we are prioritizing the restoration of public trust above any specific pro- or anti-vaccine agenda," Kennedy said. "The public must know that unbiased science—evaluated through a transparent process and insulated from conflicts of interest—guides the recommendations of our health agencies."

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Kennedy has since named eight new members to the committee, who are scheduled to have their first meeting on Wednesday.

"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 said. "Robust and transparent scientific discussion is important, so long as it is rooted in evidence and understanding."

Cassidy was a key vote in favor of Kennedy's confirmation as HHS secretary.

The ACIP is chaired by Dr. Martin Kulldorff, who was reportedly placed on a leave of absence by Harvard Medical School for his refusal to get the COVID-19 vaccine.

The committee has a vote this week on key recommendations for RSV vaccines and whether clesrovimab should be recommended for all infants below 8 months of age.

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Cassidy urged officials to postpone the meeting.