In a post on his social media platform last month, President Donald Trump argued for breaking up the combined vaccination against measles, mumps and rubella “into three totally separate shots,” having children vaccinated separately against chicken pox and not vaccinating people younger than 12 against hepatitis B so that America’s children would “take vaccine in 5 separate medical visits.”
That the president was making such a suggestion was bad enough — in part because there are no vaccines in the U.S. that guard against only measles or only mumps or only rubella. But this week, acting CDC Director Jim O’Neill echoed Trump’s statement and posted on X, “I call on vaccine manufacturers to develop safe monovalent vaccines to replace the combined MMR and ‘break up the MMR shot into three totally separate shots.’”
There are no vaccines in the U.S. that guard against only measles or only mumps or only rubella.
O’Neill is in his position after his successor as director, Susan Monarez, was fired because, her attorney says, she clashed with Health Secretary Robert F. Kennedy Jr. and “refused to rubber-stamp unscientific, reckless directives and fire dedicated health experts.”
The current MMR vaccine is safe and effective, according to the CDC, and offers 93% protection against measles with one shot and 97% protection with two shots. There is no scientific basis to separate the vaccines, and no research has shown any compelling evidence to suggest they should be separated. Splitting the vaccines apart would be an unscientific, reckless directive, and Trump and O’Neill pushing for it amounts to medical malpractice.
Though the vaccines targeting measles, mumps and rubella were all created and administered separately in the 1960s, in 1971, Maurice Hilleman, considered by many to be the father of modern vaccines, combined the three vaccines into a single shot. The goal was to reduce the number of times parents would have to bring their children in for shots and thereby increase compliance.
As the Smithsonian’s website notes: “The combined vaccine is more convenient for patients, and this convenience actually saves lives. Fewer injections translate as fewer missed doses, and therefore more protection in a shorter time. The MMR vaccine has saved millions of lives worldwide.”
If the U.S. were to force manufacturers to split the MMR vaccine three ways and formally recommend delaying the administration of the hepatitis B vaccine until the age of 12, then the government would be responsible for outbreaks of potentially deadly diseases on a scale the country has not seen in decades.
Take measles, as an example. In 1949, well before the initiation of vaccination, there were 625,281 cases of measles. Contrast that with last year in 2024, where the U.S. saw only 285 cases. Global vaccination has saved at least 154 million lives, according to the World Health Organization, with over 100 million lives being infants from childhood vaccinations like the MMR vaccine.
Already, due to vaccine hesitancy and the politicization of science, decreased vaccine rates for measles has led to deadly outbreaks. Already in America, due to vaccine hesitancy and the politicization of science, decreased vaccine rates for measles has led to deadly measles outbreaks, with two unvaccinated children dying in Texas and thousands of other children being infected throughout the country. This is occurring with just a single shot available that protects against measles, mumps and rubella (MMR); so imagine how this could be amplified if children were required to take three separate vaccines to prevent the same three diseases. The Trump administration, and specifically Kennedy, have expressed concerns about the number of vaccines in the childhood immunization schedule. In a Senate hearing in September, Kennedy wrongly said that children receive more than 90 vaccine doses before they’re 18. In reality, the childhood immunization schedule recommends that children receive closer to 30 vaccine doses from birth to 18. Ironically, by splitting the MMR vaccines into three vaccines, the Trump administration will be increasing the number of doses that children will have to receive. As for hepatitis B, which Trump says children shouldn’t be inoculated against before 12, Sen. Bill Cassidy, R-La., a doctor who launched a hepatitis B vaccination program in Louisiana and developed the hepatitis treatment plan for that state’s prison system, stated in a Senate hearing: “Before 1991, as many as 20,000 babies, babies, were infected with hepatitis B in the United States of America, and that changed when the hepatitis B vaccine was approved for newborns. Now fewer than 20 babies per year get hepatitis B from their mother.” Even if mothers are screened for hepatitis B and are found to be negative, an unvaccinated child could acquire hepatitis B later in life if interacting with other individuals positive for the virus by sharing of a toothbrush or razor or engaging in sexual activities. Why should we gamble and take a risk with our kids getting a disease that can literally kill when it is entirely preventable with a series of three shots in the first two years of life? The type of misinformation being spread by the president of the United States could have grave consequences for public health. Multiple devastating diseases that can lead to blindness, deafness, infertility, cancer and death will surge, all because of baseless recommendations that are not rooted in science. Our children deserve better.
Dr. Omer Awan
Dr. Omer Awan M.D., MPH, CIIP, is a practicing radiologist physician in Baltimore, Maryland, who writes about the most pressing issues in healthcare and public health. 
