Vaccine makers say splitting MMR shots unlikely despite Trump order

President Donald Trump's recent executive order calls for the measles, mumps and rubella (MMR) vaccine to be broken into separate injections and for other childhood shots to be spaced out. Implementing the plan would require drugmakers to revive individual vaccines that have not been sold in the United States for decades and to build new manufacturing capacity for millions of additional doses.

Health experts argue the change would increase the number of doctor visits for parents, raise costs for pediatric practices, and could reduce overall vaccination rates. Studies have shown that combination vaccines improve the likelihood that children are fully protected before school entry.

"We do things that are less convenient and more expensive if there’s a good reason to do it. There is no good justification for this. I think it’s very bad public health policy," said Dr. Anna Durbin of the Johns Hopkins Bloomberg School of Public Health.

Former FDA vaccine chief Dr. Jesse Goodman noted that companies would need to conduct large studies to demonstrate that newly produced individual shots generate immune responses comparable to the current combination, and that new manufacturing facilities would require FDA approval—a process that typically takes about five years.

"I don’t think there’s any comparable example of removing hugely effective public health measures that protect babies for no documented scientific reason," Goodman added.

Merck and GSK, the primary suppliers of the U.S. MMR vaccine, reaffirmed the safety and effectiveness of their combination products but did not indicate plans to develop separate shots. Merck stated that no scientific evidence shows a benefit to separating the vaccine.

If the MMR shot were split, the standard two-dose schedule would become six separate visits, and additional spacing of other vaccines could further increase appointment frequency. Dr. Durbin warned that the added inconvenience could lead to missed vaccinations.

"It’s going to be less convenient, more expensive and you’re going to have fewer people getting vaccinated," she said.

White House spokesman Kush Desai argued the order would give parents more timing options and ultimately raise vaccination rates. However, experts point out that the order is not legally binding; only state governments can mandate school immunizations, and the FDA cannot force manufacturers to create new products.

"They’d be competing against themselves, and there’s no reason to do that," said Dr. Paul Offit of the Children’s Hospital of Philadelphia.

Analysts predict that states are likely to ignore the directive, leaving the existing combination vaccine regimen unchanged.