Vaccines cause autism

What the research found

A 2014 meta-analysis pooled five cohort studies with 1,256,407 children and five case-control studies with 9,920 children. It found no link between vaccination and autism. This included MMR, thimerosal (a mercury-based preservative) and mercury.

Two large Danish studies followed children for years. A 2002 study of 537,303 children and a 2019 study of 657,461 children both found no higher autism risk in MMR-vaccinated children. A 2021 US systematic review rated the evidence for no increased autism risk after MMR as high strength.

The idea traces back to a 1998 report on 12 children. In that report, parents linked symptoms to the MMR vaccine, but the paper was later retracted. In late 2025, a WHO expert committee reviewed 31 more studies and again found no causal link. Australia's TGA and Chief Medical Officer made the same finding.

What it doesn’t mean

• This does not mean vaccines have no side effects. The 2021 review found MMR does raise the risk of febrile seizures. Side effects are almost always mild, such as redness and swelling where the needle went in, and disappear in a few days. Serious reactions are very rare.
• Autism is a neurodevelopmental condition with a strong genetic component, and it begins before age one. If you notice changes in your child's speech, play or behaviour, see your GP or child health nurse. Do not delay checks because of vaccine worries.
• If you are worried about vaccines, talk to your GP or child health nurse. Fewer vaccinated children has led to measles outbreaks.