A federal court hearing is set to begin Friday over the Department of Health and Human Services' vaccine schedule revision and vaccine panel overhaul under Secretary Robert F. Kennedy, Jr.

U.S. District Judge Brian Murphy, a Biden appointee, is overseeing the case, which was brought by the American Academy of Pediatrics and other plaintiffs, Reuters reported.

The medical groups are expected to ask Murphy to issue a preliminary injunction that would prevent the Centers for Disease Control and Prevention from implementing a revised childhood vaccine schedule and block Kennedy's handpicked vaccine advisory panel from holding its meeting later this month.

The plaintiffs argue that the CDC acted unlawfully last month when it reduced the number of routinely recommended childhood vaccinations to 11 and downgraded the immunization recommendations for six diseases.

They are also challenging Kennedy's decision last year to replace all 17 Advisory Committee on Immunization Practices members, whose recommendations shape vaccine practices. The new panel includes vaccine skeptics, who plaintiffs said were appointed solely because their views aligned with Kennedy's.

Last month, Murphy allowed the case to proceed, saying those allegations were "sufficient to plausibly suggest the committee is neither fairly balanced nor free of inappropriate influence," in violation of the requirements for such panels set out in the Federal Advisory Committee Act.

Justice Department attorneys argue that the plaintiffs are seeking a court-ordered ban on the HHS "receiving and giving advice on vaccines." They say the CDC has its own discretion on vaccine guidance, and that Congress, in requiring "balance" for ACIP, meant employment status and background, making their views on vaccines irrelevant.