President Trump on Sunday signed an executive order directing federal health agencies to overhaul the recommended childhood vaccine schedule, including a directive to split the combined measles-mumps-rubella (MMR) vaccine into three separate shots administered individually. The order also reduces the overall number of vaccines recommended for children, representing one of the most significant federal interventions in vaccine policy in decades.

The executive order reflects the priorities of Health and Human Services Secretary Robert F. Kennedy Jr., who has long questioned the safety and composition of the childhood vaccine schedule and has promoted the debunked theory that vaccines are linked to autism. Kennedy's appointment and continued influence over health policy have placed vaccine recommendations — traditionally set by independent scientific advisory committees — under direct executive pressure.

Public health experts and medical organizations swiftly criticized the order. The existing MMR vaccine is widely regarded by infectious disease specialists as safe and effective, and there is no approved alternative formulation that separates the three components into individual shots currently available in the United States. Critics warned that disrupting the current schedule could reduce vaccination rates and increase the risk of measles outbreaks, a disease that had seen a resurgence in parts of the country in recent years.

The directive instructs relevant agencies to study the feasibility of offering the vaccines separately and to update clinical guidance accordingly. It is not immediately clear how quickly federal health agencies would be able to implement the changes, or whether the pharmaceutical supply chain could accommodate the production of separate formulations. The order also directs a broader review of all childhood vaccine recommendations with an eye toward reducing the total number of shots administered in early childhood.

The action drew immediate political and scientific scrutiny. While supporters framed the move as giving parents more choice and addressing long-standing concerns about the pace of childhood immunization, opponents argued the order elevates discredited fringe theories over peer-reviewed science and puts children at risk. The White House has not indicated whether it plans to consult with the Advisory Committee on Immunization Practices, the expert panel that historically has guided vaccine scheduling decisions.