President Donald Trump recently signed an executive order advocating for the separation of the combined measles, mumps, and rubella (MMR) vaccine into three individual shots. Trump linked the combined vaccine to increased autism rates, a claim that medical experts have repeatedly debunked due to the lack of scientific evidence supporting it. Physicians and public health authorities warn that the move to split the vaccine is unlikely to proceed, given both the absence of scientific justification and the logistical difficulties involved.

Experts underscore that dividing the MMR vaccine into separate doses could complicate vaccination schedules and result in more missed or delayed immunizations for children. Public health professor Neil Maniar of Northeastern University emphasized that the current combined vaccine has been shown to be effective and safe, and changing it without evidence risks creating new public health challenges rather than solving any existing problems. Additionally, with the U.S. facing a surge in measles cases—the highest in decades—the timing of this policy shift could undermine efforts to improve vaccination rates.

Pharmaceutical companies Merck and GlaxoSmithKline, the main manufacturers of the MMR vaccine, show little interest in developing the separate shots due to the significant investment and regulatory hurdles involved. William Moss, a pediatrician and epidemiologist at Johns Hopkins University, stated that pursuing individual vaccines would be a poor business decision, likely taking over a decade to develop and approve. Merck also pointed to studies indicating that combination vaccines increase compliance and vaccination completion rates among children.

Health officials worry that Trump’s push to split the MMR shot could further confuse parents and increase vaccine hesitancy. Andrew Racine, president of the American Academy of Pediatrics, noted that the current administration’s rhetoric might decrease public confidence in vaccine safety at a critical time when measles outbreaks have already resulted in child fatalities. Experts urge maintaining the current combined vaccine regimen to prevent additional barriers to childhood immunization and protect public health.