A federal judge on Monday blocked portions of Health and Human Services Secretary Robert F. Kennedy Jr.’s effort to reshape U.S. vaccine policy, halting moves to reduce the number of shots routinely recommended for children.

U.S. District Judge Brian Murphy in Boston ruled in favor of the American Academy of Pediatrics and other medical groups that challenged the policy changes, arguing federal health regulators acted unlawfully in implementing Kennedy’s agenda to alter long-standing immunization guidelines.

The ruling represents a setback for the revised childhood vaccination schedule backed by Kennedy, who was appointed last year by President Donald Trump to lead the Department of Health and Human Services.

Murphy said the United States has historically relied on vaccines to reduce or eliminate diseases through a system rooted in scientific review and legal procedures. He wrote that the current effort disregarded those methods and undermined the integrity of the process.

The judge also blocked Kennedy’s 13 appointees to the Advisory Committee on Immunization Practices from continuing in their roles ahead of a scheduled March 18–19 meeting. Murphy further invalidated the votes the panel had previously taken related to vaccine recommendations.

Plaintiffs argued the CDC acted improperly when it reduced the number of routinely recommended childhood vaccinations to 11 in January and downgraded recommendations for several immunizations, including those targeting rotavirus, influenza, and hepatitis A.

They also challenged Kennedy’s decision to remove and replace the 17 experts who previously served on the advisory committee. The groups argued the reconstituted panel lacked proper balance and violated federal rules governing advisory committees.

Murphy agreed with that argument, ruling that the panel had been unlawfully formed. As a result, earlier votes to downgrade recommendations for hepatitis B vaccines for newborns and COVID-19 shots were also invalid.

The decision was welcomed by attorneys representing the plaintiffs, who called it a victory for public health and the rule of law while noting the federal government may still appeal.

The ruling comes as vaccine manufacturers and medical providers closely watch U.S. policy changes following the COVID-19 pandemic. Drugmakers, including Pfizer, BioNTech, Moderna, Merck, Sanofi, and GSK, produce vaccines used in the U.S. childhood immunization schedule.

Justice Department lawyers argued in court that Kennedy and HHS officials have broad authority to revise vaccine policies, saying the changes were intended in part to address declining public trust in vaccines in recent years.

Murphy, who was appointed by former President Joe Biden, has previously drawn criticism from Trump and his allies for decisions that blocked parts of the administration’s agenda, including elements of its immigration policies.