Do vaccines cause autism? WHO finally answers

This has been one of the most continuous and ongoing health controversies that has plagued the past three decades: the alleged linkage between vaccines and autism, or whether the former causes the latter.And the World Health Organization (WHO) listened to that controversy, yet again, and has provided answers. Recently, the WHO's Global Advisory Committee on Vaccine Safety issued a major statement reiterating that there is no scientific evidence linking vaccines with ASD.Read on to learn more.

WHO reaffirms: Vaccines do not cause autism

The World Health Organization's expert panel has reiterated a very important message to the public: vaccines are not the cause of autism. The WHO's Global Advisory Committee on Vaccine Safety, after reviewing all the extensive scientific evidence, including 31 studies published between 2010 and 2025, determined there was no causal relationship between vaccines and ASD.This decision reinforces previous reviews in 2002, 2004, and 2012 that came to the identical conclusion. The committee also addressed concerns regarding specific vaccine components, including preservatives using thiomersal (mercury) and adjuvants made of aluminum, and found no credible evidence that such components cause autism.The WHO, in its formal statement, explained that a causal relationship is considered possible only when several high-quality studies show a statistical association.

That has simply never been the case, across decades of robust research around the world.

How the controversy started

The controversy began in 1998 with a small study published in The Lancet claiming that measles, mumps, and rubella (MMR) vaccines were linked to the onset of autism. The paper was based on only 12 cases and did not involve proper scientific controls. It later became clear that there were serious ethical violations and deliberate falsification of data in this paper.

Eventually, The Lancet retracted the paper, and its author lost his license to practice medicine.

At that point, however, the fear about vaccines and autism had already spread within significant parts of the public and via the internet.That myth lingered on, despite retraction and rejection by scientific authorities, through the workings of social media, misinformation networks, and high-profile purveyors of vaccine skepticism.

Extensive research over the years has been conducted to examine causes related to autism and the safety surrounding vaccines.

What research says

Scores of very high-quality studies performed in several countries, using large populations, have never found evidence for any relationship between vaccines, including the MMR vaccine, and the causation of autism. These studies range from large, population-based studies to systematic reviews of millions of children.Similarly, research on thiomersal and aluminum, once believed to be potential causes of autism, has proven to have no link to ASD. In fact, the rates of autism continue to climb even in locations and time frames where thiomersal-containing vaccines were long since pulled from most childhood vaccine programs.Autism has more recently been seen as a complex neurodevelopmental disorder initially, with genetics as the main driver of development, although the contribution of certain prenatal factors and toxins is suspected-and none have to date been shown to implicate vaccinations.

Why the WHO statement is ‘timely’

The timing of the WHO's clear reaffirmation comes amid renewed debate in public forums and government agencies. In the United States, for example, the Centers for Disease Control and Prevention recently revised parts of its vaccine-safety webpage to insert that "vaccines do not cause autism" is not an evidence-based claim, arguing that studies have not "ruled out" all possibilities — a move that sparked controversy among scientists and health advocates nationwide.

Public health officials have warned that unclear messaging on vaccines can fuel hesitancy and distrust of one of the most effective preventive tools in medicine. Decades of research support, with clarity, how vaccines are safe and help save lives regarding international health.

Understanding Autism

Autism is a developmental disorder related to genetic and environmental components. It is recognized that much of the underlying risk in autism comes from genetics, though environmental exposures may also have an impact on development. However, vaccination has not been proven to be one of the causes. Large population studies with long-term follow-up and involving millions of children from all over the world, including research in Denmark among other countries, have shown no heightened rate of autism in vaccinated children compared to the unvaccinated.