The fear is understandable. Parents want to protect their children, and a frightening claim can linger even after the original evidence has collapsed.

The best way to answer the concern is to compare vaccinated and unvaccinated children in much larger populations. Those studies consistently find no association between MMR vaccination and autism.

What the evidence shows

Danish nationwide cohort, 2019

Researchers studied 657,461 children born in Denmark from 1999 through 2010 and followed them through August 2013. MMR vaccination was not associated with an increased risk of autism, including among children considered at higher risk.

Read the Annals of Internal Medicine study

Meta-analysis, 2014

Ten cohort and case-control studies involving more than 1.2 million children found no relationship between vaccination, MMR or thimerosal and autism or autism-spectrum disorder.

Read the Vaccine meta-analysis

Yokohama population study, 2005

Autism incidence continued to rise in birth cohorts after MMR was withdrawn in Yokohama. This is ecological population evidence—not an individual clinical trial—but it is inconsistent with MMR being a principal cause of the increase.

Read the Yokohama study

How the controversy developed

February 1998
A 12-child case series is published
The Lancet paper described 12 children and reported a proposed syndrome. Its design could not establish that MMR caused autism. The article is now marked as retracted. View the retracted record.
2004–January 2010
Conflicts and conduct are investigated
Investigative reporting documented undisclosed interests and discrepancies. In January 2010 the General Medical Council announced detailed findings of fact, including findings of dishonesty and irresponsibility against Wakefield. Read the BMJ report.
February and May 2010
Retraction, then removal from the medical register
The Lancet fully retracted the article in February. In May the GMC found Wakefield guilty of serious professional misconduct and directed that his name be erased from the register; these were separate events. Read the BMJ sanction report.
January 2011
The BMJ describes the article as fraudulent
Brian Deer's investigation compared the publication with clinical records and documented material discrepancies. Read the BMJ investigation.

Safety, stated honestly

Like any medicine, MMR can cause side effects. Most are mild and short-lived. The NHS lists effects such as soreness at the injection site, a raised temperature, a rash and feeling unwell. Rare reactions can include a fever-related seizure or a temporary reduction in blood-clotting cells.

Side effects are monitored, and the risks of measles itself include serious complications. If you are worried about a reaction or your child's medical history, ask a GP or vaccination professional rather than relying on a postcode statistic.

Read NHS advice on MMR, side effects and booking

Why timing can mislead

Signs of autism often become noticeable around the same period in early childhood when MMR is given. Events occurring close together in time do not by themselves show that one caused the other; controlled population studies are designed to test that question.

Reliable next steps

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