Health and Human Services Secretary Robert F. Kennedy Jr. on Monday said he is "retiring" all 17 members of a crucial government panel of vaccine advisors, a shocking step that could help to sow doubts about immunizations in the U.S.

"A clean sweep is needed to re-establish public confidence in vaccine science," Kennedy said in an opinion piece in the Wall Street Journal on Monday.

Kennedy is removing all members of the Advisory Committee on Immunization Practices, or ACIP, which advises the Centers for Disease Control and Prevention. The group reviews vaccine data and makes recommendations that determine who is eligible for shots and whether insurers should cover them, among other efforts.

ACIP members are independent medical and public experts who make recommendations based on rigorous scientific review and evidence. The CDC director has to sign off on those recommendations for them to become official policy.