Paul Offit knows vaccines. A trained doctor, he spent 26 years working in pediatric infectious disease and studying the rotaviruses before ultimately creating the strain that became the RotaTeq vaccine.

Havers’ departure comes just days after U.S. Health and Human Services (HHS) Secretary Robert F. Kennedy Jr. removed all members of the CDC’s Advisory Committee on Immunization Practices (ACIP) and replaced them with new appointees. It makes recommendations on use of vaccines in the U.S.