Public and political calls to separate vaccines could undermine vaccination rates, risking outbreaks of preventable diseases and child deaths, according to health experts.

The U.S. has experienced the highest number of measles cases since 2000 in 2025, a year marked by a resurgence of the disease after it was declared eliminated.

Health Secretary Robert F. Kennedy Jr. has made false claims about vaccine safety but still advocates for vaccination, highlighting the controversy surrounding vaccine misinformation.

Proposals to split the MMR vaccine would increase the number of injections children receive, potentially reducing vaccination compliance.

Developing monovalent vaccines would involve lengthy processes including clinical trials and FDA approval, despite the vaccine's long history of safe and effective use.

Since its approval in 1971, the MMR vaccine has been used as a combination, and extensive research, including studies following the discredited 1998 Wakefield paper, shows no link between the vaccine and autism.

Major vaccine manufacturers like Merck and GSK emphasize that combination vaccines are crucial for maintaining high immunization rates, and there are no approved monovalent MMR vaccines in the U.S.

The CDC and scientific consensus agree that separating the MMR vaccine into individual shots offers no safety benefits and could hinder vaccination efforts due to increased costs and reduced compliance.

President Trump initially proposed splitting the MMR vaccine, citing concerns about the combined vaccine without scientific evidence, and later directed the CDC to develop separate vaccines for measles, mumps, and rubella.

The CDC has already recommended separating the varicella vaccine from MMR for children under 4 due to a small increased risk of febrile seizures, and Trump has supported this move.

Currently, no monovalent vaccines are approved in the U.S., and there is no scientific evidence supporting the benefit of separating the MMR vaccine.

The acting CDC director called for the development of monovalent vaccines, aligning with Trump’s stance, despite a lack of scientific support for the benefits of separation.