A new study has further dispelled the myth of a link between the measles, mumps, and rubella (MMR) vaccine and the onset of autism. Following over half a million children for more than a decade, the research found the MMR vaccine does not trigger autism, even in children with high specific autism risk factors.

One of the goals behind the newly published study from researchers at Statens Serum Institut in Denmark was to examine whether the MMR vaccine triggers autism, not just in all children generally, but more specifically in children with already heightened risk factors for autism. In order to do this the researchers looked at a decade of data from more than 650,000 children. Each child was associated with an autism risk score based on a large variety of factors known to increase an individual's propensity to develop the condition. Alongside siblings with autism and family history, these risk factors included an older father or mother, low birthweight, preterm birth, large head, assisted birth, and smoking in pregnancy.

Even after adjusting for all these factors the researchers found that the MMR vaccine is not a trigger for autism. So, subgroups of children with the highest autism risk score not only did not display incidences of the condition being triggered by the vaccine, but there was no indication of autism diagnoses being clustered around certain time periods associated with vaccinations.

"This high quality Danish study is very reassuring for anyone concerned about a possible link between MMR vaccine and autism," says Michael Baker, from the Department of Public Health at the University of Otago, Wellington. "These results should help to reassure parents that MMR vaccine is extremely safe to use."

This massive, granular study offers as certain a conclusion as science can get, accompanying a larger volume of prior epidemiological research finding absolutely no connection between autism and the MMR vaccine. To some scientists, the ongoing research disproving the vaccine-autism myth is a frustrating waste of human resources that could be allocated to more useful investigations. However, the current resurgence of measles in the United States suggests vaccine safety is still a cause of concern for many parents, and the World Health Organization (WHO) recently added vaccine hesitancy to its list of major threats to global heath in 2019.

At the very least the hope behind this new study is that any specific concern of a connection between the MMR vaccine and autism can be definitely assuaged. This is undeniably a rigorous and conclusive piece of research.

"I think this reasonably puts to bed the notion that MMR might trigger autism in susceptible subgroups of children," says Helen Petousis-Harris, a lecturer in Vaccinology from the University of Auckland. "The coffin is both nailed and superglued shut then hermetically sealed."

The new research is published in the journal Annals of Internal Medicine.