More than 20 years ago, Andrew Wakefield came up with a hypothesis linking the measles, mumps and rubella (MMR) vaccine to autism. The paper proposing the connection was retracted for methodological issues, and Wakefield’s medical license was revoked for misconduct related to those studies. But his ideas have taken hold on the Internet, where parents concerned about what they see as the toxic ingredients in vaccines, as well as the number of vaccines young infants receive in their first few years, are fueling the so-called anti-vaccine movement.
Measles outbreaks, which are primarily affecting unvaccinated children, are continuing in a number of U.S. states, fueled by the rising number of parents who are opting out of vaccinations for their kids because of safety questions they have.
Scientifically, these questions have already been answered: study after study has found no link between the MMR vaccine and autism. Now, in a new report published in the Annals of Internal Medicine, researchers in Denmark provide even more evidence that measles, mumps and rubella vaccinations are not connected to a higher risk of developing autism. In this study, the scientists addressed some potential criticisms of how previous studies were designed in order to provide additional evidence to inform concerned parents.
“We see vaccine skepticism growing,” says the study’s lead author Anders Hviid, an investigator at the Statens Serum Institut, the national public health organization in Denmark. “So we thought it was a good idea to revisit the hypothesis and try to get scientific answers to the different criticisms from skeptics of the original study.”
Hviid and his colleagues analyzed data involving more than 650,000 children born in Denmark between 1999 and 2010, and followed them for up to 13 years. Because Danish identification records include detailed health information, the team could link MMR immunizations and autism diagnoses.
Overall, the children vaccinated with MMR did not develop autism at a significantly different rate than those who were not vaccinated. The researchers also separately analyzed children who might be at higher risk of developing the disorder, including those from families with other siblings with autism, or children with risk factors for autism. They found no higher rate of autism among these children. The researchers also looked at the timing of autism diagnoses and found that they did not cluster soon after an MMR vaccination. They found no higher rate of autism among kids who received other childhood vaccinations.
Hviid and his colleagues published similar work in 2002 that found no link between MMR vaccination and autism. But the latest work includes more autism cases — it is one of the largest studies investigating the connection — and a more in-depth breakdown of the cases by autism risk factors and the timing of diagnoses.
By looking specifically at the children who might be at highest risk of autism, and finding no significantly higher rate of the developmental disorder, Hviid hopes the data will reassure parents who are concerned about the safety of the MMR vaccine. “There are a significant group of parents who are concerned and encounter this idea about vaccines causing autism or cancer on social media, or even from politicians and celebrities,” he says. “We hope that data can reduce some of that concern and convince people that the vaccine doesn’t cause autism.”