
US President Donald Trump has signed an executive order calling for changes to the way childhood vaccines are administered, including splitting the MMR vaccine against measles, mumps and rubella into three separate vaccines.
According to the order, vaccines for the three diseases should be administered at separate medical visits, once separate vaccines for each disease become available in the US.
During the signing ceremony at the White House, Trump said the MMR vaccine should be divided into three injections and given at different times.
The president also suggested that the combination vaccine could be "quite deadly" when administered all at once, comparing the amount of vaccine to a bottle of booze.
These statements have caused strong reactions from public health experts and some American politicians.
CDC rejects risk argument
According to the Centers for Disease Control and Prevention (CDC), there is no published scientific evidence that shows that dividing the MMR vaccine into three individual vaccines provides any safety benefit.
The CDC notes that the MMR vaccine can very rarely cause serious allergic reactions and there is a very small risk of seizures associated with fever. However, the agency says the vaccine is much safer than getting measles, mumps, or rubella.
Vaccine safety experts at the CDC and the American Academy of Pediatrics also do not consider the MMR vaccine to be the cause of the increase in autism diagnoses.
Criticism also from Republicans
The opposition has not only come from Democrats.
Republican Senator Bill Cassidy, a physician and chairman of the Senate Health Committee, directly criticized Trump's order.
Cassidy said the change is wrong and that splitting vaccines will mean children have to get more shots and more doctor visits to get the same protection.
According to him, this could increase vaccine hesitancy and, ultimately, make children less protected.
Individual vaccines are currently not available.
Another practical problem is that there are currently no separate licensed measles, mumps, and rubella vaccines in the US to replace the combined MMR vaccine.
Pharmaceutical companies will need to develop and go through clinical and regulatory processes to bring these products to market.
Meanwhile, requiring children to be vaccinated at different visits can make the process more costly and difficult for families.
Concerns about the increase in measles cases
The decision comes at a time when measles cases in the US during 2026 have already exceeded the number recorded in all of last year, according to data cited by Axios.
Experts warn that the increase in the number of medical visits could bring another risk: some families may not complete all the necessary visits, leaving children partially unvaccinated.
It also remains unclear whether health insurance companies will cover the costs of additional visits that would be required by the new scheme.
Another clash over vaccine policy
The new order marks another intervention by the Trump administration in American childhood vaccination policy.
Health Secretary Robert F. Kennedy Jr. and his chosen advisers have previously supported the idea of splitting the MMR vaccine and broader changes to the vaccination schedule.
However, several administration attempts to limit the federal list of recommended vaccines have been blocked by the courts.
The debate is expected to continue, especially as political arguments clash with recommendations from U.S. health authorities. The main topic of discussion remains whether changing the MMR schedule will improve children's safety or create new barriers to vaccination.