For those who battle tirelessly against the never ending onslaught of anti-vaccine propaganda, misinformation, and fear, there was great news the other day from Merck. The pharmaceutical company, and maker of the MMR vaccine against measles, mumps, and rubella, has decided not to resume production of the individual, or “split”, components of the vaccine. A Merck representative made the announcement during a meeting of the CDC Advisory Committee on Immunization Practices (ACIP) on Tuesday. During previous ACIP meetings, science experts on that committee presented compelling arguments against  continued, large scale production of the monovalent components of the MMR vaccine, which were echoed by scientists in Merck’s vaccine division. In a moment, I’ll discuss the arguments against the split vaccine, and why this is so important a decision. First, some background on the issue of splitting the MMR.

Merck has manufactured individual measles, mumps, and rubella vaccines on a small scale for various reasons. For example, the monovalent measles vaccine has been recommended during measles epidemics to protect infants 6-12 months of age from infection, and rubella vaccine is given to women without immunity, to protect against congenital rubella syndrome in future pregnancies. But since 1967, the MMR vaccine has been the primary source of protection against measles, mumps, and congenital rubella. The  original recommendation for the use of the combination vaccine at 12 months of age, and the recommendation in 1989 to add a booster dose at 4-6 years, has led to the near eradication of these diseases in the US. But in 1998, the infamous Andrew Wakefield warned the public to avoid the MMR vaccine, and instead opt for the monovalent components, spread out over time. This announcement came during a press conference to announce his also infamous, and thoroughly discredited Lancet paper linking the MMR vaccine to autism. It came as a shock to all of us who understand the importance of the MMR vaccine, and who know of no scientific rationale to split the vaccine. Wakefield claimed he had reason to believe the combined vaccine might lead to autism in some children. Of course, his reason was not based on any scientific evidence, and we now know that he had an undisclosed financial incentive to push people toward a monovalent measles vaccine. To this date, not a single shred of science supports the notion that the MMR vaccine causes autism, nor are there any scientifically plausible reasons that it would. As we know, mountains of data point to just the opposite conclusion. Despite absolutely no scientific rationale for splitting the MMR vaccine, and despite the fact that all of Wakefield’s claims about the MMR vaccine and autism have been thoroughly debunked, the myth lives on. I am still confronted by parents who are worried about the vaccine, and who request, or at least ask about, splitting the vaccine. On my local parents list-serve, the issue constantly rears its head, and each time I attempt to step in to reassure and educate, I am met with a wall of fear and opposition. Because of this irrational fear, pockets of unimmunized children have set the stage for disease outbreaks, and have already led to outbreaks around the country. Just this week I received an alert from the NYS DOH about a mumps outbreak in my own backyard, similar to an alert in July about a measles outbreak. Unbelievably, this doesn’t seem to phase the many parents who have fallen victim to the growing epidemic of vaccine fear.

There are several reasons Merck’s decision about the MMR vaccine is so important. In addition to creating the need for more doctor visits, with more shots, more pain, and at greater cost, splitting the vaccine into individual components prolongs the vaccination process (each component must be separated by at least a month to insure efficacy), increasing a child’s vulnerability to disease. Administration of separate components over prolonged intervals is also less likely to result in completion of the series, than is administration of a single vaccine. But perhaps more importantly, this decision is a vote against irrationality and an anti-scientific worldview that has begun to endanger society. Many parents will be upset and disappointed by Merck’s decision, especially those who were just recently reassured by Dr. Sears that Merck was poised to reintroduce the separate components in 2011. The fact is, this was actually a bad decision for Merck from a purely economic perspective. It costs considerably more to manufacture, produce, and test combination vaccines than monovalent vaccines.  Selling three individual components would also produce more revenue than a single combination product. Nevertheless, the anti-vaccine lobby will most assuredly find a way to paint this decision as a picture of government-industry conspiracy, intent on covering up the truth and depriving parents of a safer choice. One could say “you never win”, but for now I’m just happy we did.


Posted by John Snyder

John Snyder, MD, FAAP, is an Assistant Professor of Pediatrics at Tufts University School of Medicine, and a practicing pediatrician at Amherst Pediatrics in Amherst, Massachusetts. Previously, he was Medical Director of the teaching clinic at Baystate Children's Hospital, and before that he was Chief of the Section of General Pediatrics and Medical Director of Pediatric Ambulatory Care at Saint Vincent's Hospital in New York City. Since 1994, Dr Snyder has been active in pediatric resident and medical student education with a particular interest in evidence-based pediatrics. His main area of interest is medical myth and the ways in which parents utilize information in making medical decisions for their children. One area of focus has been the vaccine myth, and he lectures frequently on this subject in both academic and community settings. His other activities have included: contributor to the Gotham Skeptic blog, member of the New York City Skeptics' board of advisors, and expert for ("A New Social Network on Health Founded by America's Top Doctors"). Dr Snyder graduated from Mount Sinai School of Medicine, completing his residency training in pediatrics at The Mount Sinai Hospital in New York City. He is board certified in pediatrics, and is a Fellow of The American Academy of Pediatrics. Dr. Snyder has no ties to industry, and no conflicts of interest regarding any of his writings. Dr. Snyder’s posts for Science-Based Medicine are archived here.