US District Judge Brian Murphy in Boston sided with the American Academy of Pediatrics and other medical groups on Monday, which said health regulators had acted unlawfully to carry out Kennedy's agenda of upending immunisation policies and warned the changes will reduce vaccination rates and harm public health.
Murphy's ruling forced the Advisory Committee on Immunization Practices (ACIP) to postpone a meeting set to begin on Wednesday, after he concluded it was not lawfully constituted and blocked Kennedy's 13 appointees to it.
The ruling dealt a significant setback for the reduced childhood vaccination schedule championed by Kennedy, a longtime anti-vaccine activist appointed last year by President Donald Trump to lead the Department of Health and Human Services (HHS). The Trump administration will likely appeal the decision.
Murphy said that for decades, the US had been focused on the eradication and reduction of diseases using vaccines, which were developed through "a method scientific in nature and codified into law through procedural requirements".
Under Kennedy, Murphy said, the government "has disregarded those methods and thereby undermined the integrity of its actions".
The judge blocked Kennedy's 13 ACIP appointees from continuing to serve in their positions and upended votes they had previously taken to reshape vaccine policies.
"This is a great victory not only for vaccines and public health in the United States, but for science," said Richard Hughes, a lawyer for the plaintiffs.
HHS spokesperson Andrew Nixon said the department "looks forward to this judge's decision being overturned just like his other attempts to keep the Trump administration from governing".
The plaintiffs had argued that the US Centers for Disease Control and Prevention acted unlawfully when it cut the number of routinely recommended childhood vaccinations to 11 and downgraded the immunisation recommendations for six diseases, including rotavirus, influenza and hepatitis A.
Murphy agreed, saying the CDC lacked authority to unilaterally change the immunisation schedule without consulting ACIP, which makes recommendations that shape US vaccine practices and insurance coverage.
And he said the committee itself was unlawfully constituted and no longer complied with the Federal Advisory Committee Act's requirements for balance after Kennedy last year removed and replaced all 17 independent experts who previously served on the panel.
The plaintiffs said the panel was now dominated by people aligned with Kennedy's anti-vaccine views, and Murphy said that of 15 current ACIP members, most appear "distinctly unqualified".
"A committee of non-experts cannot be said to embody 'fairly balanced ... points of view' within the relevant scientific community", Murphy wrote.
Because the committee was unlawfully constituted, earlier votes by the panel to downgrade recommendations for hepatitis B vaccines for newborns and COVID-19 shots broadly were also invalid.
Groups aligned with Kennedy's Make America Healthy Again movement like Children's Health Defense, an anti-vaccine group co-founded by Kennedy, and the Independent Medical Alliance, characterised the decision as judicial overreach and argued that the changes advocated by the committee should not be controversial.
