On Friday, President Trump doubled down on calling for changes to the measles, mumps, and rubella vaccine. “BREAK UP THE MMR SHOT INTO THREE TOTALLY SEPARATE SHOTS (NOT MIXED!),” he wrote on his Truth social account.
Currently, parents are offered either the MMR vaccine or a one-shot combination of measles, mumps, rubella, and varicella (chickenpox) for their children. The combined, quadrivalent shot comes with a slight increased risk of febrile seizures if given before age four, so the CDC and many medical experts recommend that physicians to administer as two shots if possible. But, there is scant evidence to suggest dividing the MMR vaccine up further — and spreading the shots out over time — provides any health or safety benefit. And the added burden of going to the doctor’s office multiple times risks a decline in vaccination coverage.
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“There’s no scientific evidence that separating the vaccines provides any medical benefit. I can say that unequivocally,” said Jake Scott, an infectious disease physician at Stanford University. “In fact, all of the evidence points in the opposite direction, that the combined vaccine provides equal safety and efficacy, with fewer injections and better compliance.”
Trump initially suggested separating out the MMR vaccine during a press conference Monday, where he and other top officials also pushed a link between the use of acetaminophen during pregnancy to increasing rates of autism. (Experts say the link between autism and Tylenol is unclear, and the American College of Obstetrics and Gynecology has affirmed the benefit of acetaminophen during pregnancy.)
Trump’s Friday comments go further, suggesting a departure from current vaccine policy that even his administration’s vaccine advisers have not publicly considered. Earlier this month, the Centers for Disease Control and Prevention’s vaccine advisory committee voted to recommend that children under four receive the varicella vaccine as a separate shot (a recommendation the CDC already includes on its website.) It did not consider breaking MMR into three different shots.
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Trump has presented no new data to suggest the combined MMR vaccine poses risks that have not been considered by physicians or advisory panels. While it is unclear where Trump initially got the idea to separate out the shots, the most vocal proponent of such a move is Andrew Wakefield — a now infamous British anti-vaccine advocate who published a paper in 1998 purporting to show a connection between MMR vaccines and a rise in autism. That paper has since been retracted, and Wakefield was taken off the U.K.’s medical register.
Following Trump’s initial comments on Monday, Wakefield posted a message of support, saying that the president was adopting “Wakefield recommendations on separating MMR and calls for major reforms in the childhood vaccine schedule.”
“I haven’t heard anyone make that claim in years, actually, since Andrew Wakefield did that years ago,” said William Moss, director of the International Vaccine Access Center at Johns Hopkins University. “So I’m actually quite shocked that Trump would propose that, but the bottom line is, there’s absolutely no rationale to separate those out, and monovalent vaccines aren’t even available in the United States.” He added that while Trump’s comments are concerning, the President can’t unilaterally change vaccine policy.
A spokesperson for the Department of Health and Human Services declined to comment, deferring to the White House, which did not respond to questions regarding whether the FDA or the Advisory Committee on Immunization practice would pursue officially recommending monovalent vaccines.
Is it possible to get separate measles, mumps, and rubella vaccines?
No. The monovalent vaccines for measles, mumps and rubella were phased out in the U.S. in 2009 because of the success of the combined vaccine. There are currently three MMR vaccines approved by the FDA, and they are all combined vaccines.
Making monovalent vaccines available would likely take years. The vaccines would have to undergo a length review process, including the conducting of new clinical trials, reorienting vaccine development pipelines, and applying for FDA approval, Scott notes.
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What are the risks associated with the MMR vaccine?
Hundreds of millions of MMR vaccine shots have been given around the world. The vaccine is extremely effective in preventing disease, and researchers have found the risks of side effects are minimal. There is a small increased risk of a febrile seizure in children in the 12 days after receiving an MMR vaccine. At ACIP’s recent meeting of the s, a CDC scientist put that risk at one additional seizure per 3,000-4,000 vaccinations.
Taking the MMRV shot seems to increase the risk of febrile seizures slightly, which is why even when ACIP initially voted to approve the MMRV shot in 2009, they continued to recommend the two shots (though parents were allowed to request the MMRV vaccine, if it made sense for their child.) According to the CDC, “Febrile seizures can be frightening, but nearly all children who have a febrile seizure recover quickly. Febrile seizures do not cause any permanent harm and do not have any lasting effects.”
What could happen if monovalent vaccines become more common?
Experts worry that if the administration tries to break up the MMR shot, it could lead to lower rates of coverage, because it would increase the burden on parents and pediatricians. In one study, 69% of children who received a combination vaccine completed the recommended series — compared to the 50% that opted for the single antigen vaccines.
“Whatever their intent is, the outcome is totally predictable. It’s lower vaccination rates, more disease and more kids dying from preventable illness,” Scott said. “Proposing to separate vaccines that can’t be separated, the only practical effect of that is to make parents question the current schedule.”
Trump’s rhetoric comes just months after the U.S. experienced the largest measles outbreak in decades. A recent study found that the outbreak was worsened by particularly low vaccination rates in Gaines County, Texas. “These events underscore the challenges in maintaining community immunity in the setting of vaccine hesitancy and disruption of routine vaccination programs, including drops in MMR coverage,” the researchers wrote in their paper.
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The move to favor monovalent vaccines is also a contradictory move for the administration. Health Secretary Robert F. Kennedy Jr. has repeatedly decried the number of vaccines children get — which would only increase with monovalent vaccines.
Experts STAT spoke to also reiterated that the combined vaccine has been available for over half a century — and helped lead to the elimination of measles and rubella in the U.S. in the early aughts.
“Since then, the door has been opened for the reintroduction of, particularly measles, the most contagious of the three, because there are some parents who are withholding their children from vaccination,” said William Schaffner, an epidemiologist and professor of public policy at Vanderbilt University.