The acting chief of the Centers for Disease Control and Prevention on Monday called for the combination measles, mumps, and rubella vaccine to be broken up into three separate shots, a move that would turn back the clock on more than fifty years of vaccine policy.
Acting CDC director Jim O’Neill suggested the MMR be split up in a social media post, just after U.S. President Donald Trump also made a similar argument in his own post. There’s no evidence that the combined MMR, or the childhood vaccination schedule in general, is in any way dangerous to children—a reality that the CDC still acknowledges on its website (for now at least). There is also no evidence that breaking up the MMR would be safer. Rather, it could make it incredibly hard for parents to get their children fully vaccinated—not least because the separate vaccines don’t actually exist in the U.S.
In his post, O’Neill called for vaccine makers to make individual shots for all three diseases—the separate shots were abandoned in the 1970s because the combined MMR was so effective. It’s a stance that O’Neill, also deputy HHS secretary, is standing by.
“Deputy Secretary O’Neill agrees with President Trump that immunizations for measles, mumps, and rubella would be best administered as three separate vaccines,” a HHS spokesperson told Gizmodo, adding that “standalone vaccinations can potentially reduce the risk of side effects and can maximize parental choice in childhood immunizations.”
Logistical hurdles aside, however, there’s simply no good reason why the MMR vaccine should be separated, and doing so could actively endanger children and increase their risk of encountering these diseases.
Why three in one?
Scientists first developed vaccines for measles, mumps, and rubella in the 1960s, while the first combination MMR vaccine was developed in 1971. Effective and far easier for parents to access because it required fewer doses to reach full immunity from all three diseases, the shot rapidly became the global gold standard. In 2005, a new vaccine that added protection against varicella (chickenpox) became available as well, the MMRV vaccine, although it is far less commonly used.
Over the decades, the MMR vaccine has prevented countless infections and deaths from all three diseases. Extensive studies have validated its safety and shown that the vaccine’s overall benefits outweigh any potential harms, with serious side effects like anaphylaxis (a severe allergic reaction) seen only very rarely.
An important advantage of the MMR vaccine, which is given to children twice by the age of six, is its convenience. Parents are more able and more likely to vaccinate their children against these diseases because it only requires two doses of one vaccine, as opposed to six doses of three vaccines.
But anti-vaccine advocates have long contended that giving children too many vaccines at once can be dangerous, and have specifically called for combination vaccines like the MMR to be broken up, despite having no new evidence to support their cause.
Why is there so much focus on the MMR?
Anti-vax claims about the MMR reached a fever pitch in the late 1990s, when a British doctor named Andrew Wakefield published a study in the Lancet claiming to show a link between autism and the MMR vaccine. At the time, Wakefield called for the MMR vaccine to be separated into three vaccines as a precaution.
Investigative journalist Brian Deer and others quickly discredited Wakefield’s study, showing how he had fraudulently manipulated data to get the conclusions he wanted. Deer also revealed that Wakefield held a patent for a single measles vaccine, meaning he could have potentially profited handsomely if he convinced the world to break up the MMR shot. The Lancet later retracted the study, and Wakefield was struck off the UK’s medical register as a result of Deer’s investigation. Notably, many other studies have failed to find any link between autism and the MMR vaccine (or, for that matter, a link between autism and any vaccine at all).
But Wakefield’s failed campaign hasn’t stopped anti-vaccine sentiment from growing, and the movement is unfortunately now stronger than ever, in part thanks to the rapid ascension of Robert F. Kennedy Jr., a long time vaccine skeptic, to lead the U.S. Department of Health and Human Services.
RFK and vaccines
Since taking up his post as HHS secretary this year, Kennedy has made a series of appointments and changes that, taken together, have undermined vaccine science.
Kennedy in June fired all 17 members of the CDC’s Advisory Committee on Immunization Practices—outside experts who help steer the country’s vaccine policies—and handpicked new members that have voiced vaccine skepticism or outright anti-vaccine sentiments in the past. Since then, the new ACIP has recommended removing or limiting the use of several vaccines based on what other experts describe as weak or misleading evidence.
His first CDC director, Susan Monarez, claimed that she was fired in August for refusing to rubber stamp ACIP’s recommendations. Her departure saw Jim O’Neill—a biotech investor and Kennedy backer who has no medical training—installed as acting CDC director.
And late last month, Kennedy appeared at the White House with Trump to talk about autism and Tylenol use in pregnancy (for more on that, see here). There, Trump went out of his way to seemingly suggest that vaccines are also to blame for rising autism rates, saying that “too many liquids” were given to children and calling for the MMR shots to be broken up.
Do single vaccines for measles, mumps, and rubella exist?
Single vaccine formulations of measles, mumps, and rubella were developed in the 1960s, but no such vaccines are approved for use in the U.S. today. That complete lack of vaccine supply means it is unclear if and how a transition to single vaccines could even occur should the acting CDC director’s suggestion move closer to fruition.
And again, there’s no credible evidence that combination vaccines, or the childhood vaccination schedule in general, are dangerous or have any links to autism.
This fight is coming at a particularly fraught moment: There is an ongoing measles outbreak in the U.S., and public health experts have sounded the alarm over declining vaccine rates across the country. But given how much Kennedy and his allies have already reshaped the country’s public health infrastructure, there’s really no telling what could happen next.