Study of over 1 million children finds no link between MMR vaccine and autism

A new Australian study has found no evidence whatsoever of a link between the MMR vaccine and autism development in children. It also found no evidence of a link between thiomersal, a mercury compound used in very small quantities as a preservative in some vaccines, and autism development. (Thiomersal is no longer found in any of the vaccines used in the UK routine childhood schedule.)

Fears that the MMR vaccine might be linked to autism development led to a fall in MMR vaccination rates in previous years. As a result, there have been many more cases of measles worldwide. As well as the outbreaks in Wales in 2012, the US saw 17 measles outbreaks in 2011.

Researchers at the University of Sydney carried out a systematic review and meta-analysis of 10 studies, all of which had independently examined the question of whether there might be a link between autism development and the MMR vaccine or thiomersal in vaccines. A meta-analysis combines data from several original studies, and the results can often be more powerful and informative than the results of each individual study. In total, over 1.25 million children from four different countries were included in this analysis. The size of the study is important, because it enabled the researchers to identify if there might be any rare effects linked to the vaccine that might only show up in a very few people.

The study found no relationship between:

  • vaccination and autism
  • vaccination and ASD (autism spectrum disorder)
  • autism/ASD and MMR
  • autism/ASD and thiomersal
  • autism/ASD and mercury in vaccines

Overall, this strongly suggests that vaccinations are not associated with the development of autism or autism spectrum disorder. The results are in line with the findings of a systematic Cochrane review in 2012, which looked at over 60 smaller studies and found no qualitative evidence for a link between the MMR vaccination and autism.

Read the abstract of the Australian study

More information about thiomersal in vaccines in the UK