The MMR vaccine causes autism

The MMR vaccine causes autism
	FALSE
	"The combined measles, mumps and rubella (MMR) vaccine causes autism in children, through a bowel disorder or otherwise."
Domain	Health & Medicine
Tactic	Manipulation; Pseudoscience / Junk Science;
Era	Current
First seen	1998
Origin	Paper by Andrew Wakefield and colleagues in The Lancet, 28 February 1998, and an accompanying press conference
Last reviewed	2026-10-26
	Further reading: books on Health & Medicine

The claim that the MMR vaccine causes autism grew out of a small 1998 study led by the British gastroenterologist Andrew Wakefield. The paper was later shown to rest on manipulated data, undisclosed financial conflicts and unethical research practices. It was fully retracted in 2010, and Wakefield lost his medical license. Studies involving millions of children have found no link between the vaccine and autism. Yet the claim helped drive down vaccination rates and contributed to the return of measles in places where it had been nearly eliminated, and it remains a pillar of anti-vaccine movements worldwide.

The claim

In its original form, the claim held that the MMR vaccine triggered a new syndrome of bowel inflammation, which in turn allowed harmful substances to reach the brain and cause developmental regression, including autism. Over time, the claim simplified into the belief that "vaccines cause autism," often extended to other vaccines and ingredients.

Origin

On 28 February 1998, The Lancet, one of the world's leading medical journals, published a paper by Wakefield and 12 co-authors from the Royal Free Hospital in London. It described 12 children with bowel problems and developmental disorders, and reported that in eight of them, parents or doctors linked the onset of symptoms to the MMR vaccination.

The paper itself acknowledged that it did not prove a causal link. But at a press conference organized by the hospital, Wakefield said he could not support continued use of the combined vaccine and recommended that children receive separate single vaccines instead. That message, not the paper's cautious language, dominated news coverage.

How it spread

British media gave the claim enormous attention over the following years, often presenting it as a debate between equal sides: a maverick doctor and worried parents against the medical establishment. In 2001 and 2002, coverage intensified. Public figures declined to say whether their own children had received the vaccine, which fed suspicion.

Vaccination rates fell. In England, MMR coverage at age two dropped from about 92 percent before the paper to around 80 percent in the early 2000s, and much lower in some areas, well below the roughly 95 percent needed to prevent measles outbreaks. Measles cases rose, and in 2008 measles was declared endemic in England and Wales again for the first time in 14 years.

The claim crossed the Atlantic and spread through the early internet, parenting forums, celebrity advocacy and, later, social media. It merged with other vaccine fears, including concerns about the preservative thimerosal, which was removed from routine childhood vaccines in the United States around 2001 as a precaution, without any change in autism trends afterward.

How it was exposed

Starting in 2004, the investigative journalist Brian Deer reported in The Sunday Times that Wakefield had been paid by lawyers seeking evidence for a lawsuit against vaccine manufacturers, and that some of the children in the study had been referred through those lawyers. These conflicts had not been disclosed to The Lancet. Deer also reported that Wakefield had filed a patent for a single measles vaccine, a potential rival to MMR. That year, 10 of the paper's 12 co-authors issued a statement retracting the paper's interpretation.

The UK's General Medical Council then conducted the longest misconduct hearing in its history. In January 2010 it found that Wakefield had acted dishonestly and irresponsibly, including subjecting children to invasive procedures such as colonoscopies and lumbar punctures without proper ethical approval. On 2 February 2010, The Lancet fully retracted the paper. In May 2010, Wakefield was struck off the UK medical register.

In 2011, the BMJ published a series by Deer comparing the paper with the children's medical records. It concluded that the case histories had been altered: in several children, symptoms described as beginning after vaccination had begun before it, and some children reported as previously normal had prior developmental concerns. The BMJ's editors described the study as an "elaborate fraud." Wakefield has denied wrongdoing.

What the evidence shows

Large studies in many countries have found no association between the MMR vaccine and autism. Among the largest:

A Danish study of more than 537,000 children, published in the New England Journal of Medicine in 2002, found no higher autism rate among vaccinated children.
A follow-up Danish study of more than 650,000 children, published in the Annals of Internal Medicine in 2019, again found no increased risk, including among children with a sibling with autism.
Reviews by the US Institute of Medicine, the World Health Organization and the Cochrane Collaboration reached the same conclusion.

Autism diagnoses have risen in many countries, largely because of broader diagnostic criteria, greater awareness and better screening. The signs of autism often become noticeable around the age at which children receive MMR, between 12 and 15 months, which makes it easy for parents to perceive a link in time that is not a link in cause.

Why it persisted

Timing creates a powerful but misleading story of before and after.
Parents seeking answers about a life-changing diagnosis were offered a clear cause and a villain.
Early media coverage presented a fringe claim and a scientific consensus as equal sides.
Wakefield continued promoting the claim from the United States, including through the 2016 film Vaxxed. Anti-vaccine activism contributed to a 2017 measles outbreak among the Somali-American community in Minnesota, where MMR coverage had fallen sharply.

Lessons for readers

A single small study, especially one without a control group, cannot establish cause, however prominent the journal.
Check for undisclosed financial interests.
"Some people say X, others say Y" coverage can mislead when the evidence overwhelmingly supports one side.
Before-and-after timing is not evidence of causation.

Sources

A. J. Wakefield et al., "Ileal-lymphoid-nodular hyperplasia, non-specific colitis, and pervasive developmental disorder in children," The Lancet 351 (1998). Retracted 2010.
The Editors of The Lancet, "Retraction—Ileal-lymphoid-nodular hyperplasia...," The Lancet 375 (2010).
Brian Deer, "How the case against the MMR vaccine was fixed," BMJ 342 (2011); and Fiona Godlee et al., "Wakefield's article linking MMR vaccine and autism was fraudulent," BMJ 342 (2011).
Kreesten M. Madsen et al., "A Population-Based Study of Measles, Mumps, and Rubella Vaccination and Autism," New England Journal of Medicine 347 (2002).
Anders Hviid et al., "Measles, Mumps, Rubella Vaccination and Autism: A Nationwide Cohort Study," Annals of Internal Medicine 170 (2019).