A federal judge on Monday blocked key parts of Health Secretary Robert F. Kennedy Jr.'s effort to reshape U.S. vaccine policy, including a move to reduce the number of shots routinely recommended for children.

U.S. District Judge Brian Murphy ​in Boston sided with the American Academy of Pediatrics and other medical groups, which said health regulators had acted unlawfully to ‌carry out Kennedy’s agenda of upending immunization policies and warned the changes will reduce vaccination rates and harm public health.

The ruling dealt a significant setback for the reduced childhood vaccination schedule championed by Kennedy, a longtime anti-vaccine activist appointed last year by Donald Trump to lead the U.S. Department of Health and Human Services.