A WHO global expert committee on vaccine safety found that, based on available evidence, "no causal link exists between vaccines and autism spectrum disorders (ASD)." The analysis, covering 31 primary research studies published between January 2010 and August 2025, "strongly supports the positive safety profile of vaccines used during childhood and pregnancy, and confirms the absence of a causal link with ASD." The committee concluded that "vaccines, including those with thiomersal and/or aluminum, do not cause autism."

The 2011 Institute of Medicine (IOM) report "Adverse Effects of Vaccines: Evidence and Causality" reviewed 158 potential vaccine–adverse event pairs, including the relationship between measles-mumps-rubella (MMR) vaccine and autism. In its findings, the committee stated that the evidence "favors rejection of a causal relationship" between MMR vaccine and autism. The report also concluded more broadly that "few health problems are caused by or clearly associated with vaccines."

This review states that "despite the overwhelming data demonstrating that there is no link between vaccines and autism, many parents are hesitant to immunize their children." It notes that numerous epidemiological studies "failed to show any association between the measles-mumps-rubella (MMR) vaccine and autism" and that large population-based studies also "found no evidence" that thimerosal-containing vaccines increase autism risk. The article characterizes the vaccine–autism connection as a "myth" not supported by scientific evidence.

In this nationwide cohort study of Danish children born from 1999 through 2010, the authors wrote: "We found no support for the hypothesis of increased risk for autism after MMR vaccination in a nationwide unselected population of Danish children." They reported that, during 5,025,754 person-years of follow-up, 6,517 children were diagnosed with autism and that "comparing MMR-vaccinated with MMR-unvaccinated children yielded a fully adjusted autism hazard ratio of 0.93 (95% CI, 0.85 to 1.02)." The conclusion stated: "The study strongly supports that MMR vaccination does not increase the risk for autism, does not trigger autism in susceptible children, and is not associated with clustering of autism cases after vaccination."

The CDC page summarizes findings from federal reviews, noting that the measles-mumps-rubella (MMR) vaccine "has been studied regarding autism" and that reviews from the Institute of Medicine (IOM) and the Agency for Healthcare Research and Quality (AHRQ) "maintain with a high strength of evidence that there is no association with autism spectrum disorders based on observational evidence only." For other routine infant vaccines (such as DTaP, HepB, Hib, IPV, and PCV), the page explains that the IOM’s 2012 report found that the evidence was "inadequate to accept or reject a causal relationship" with autism, and AHRQ’s 2014 and 2021 assessments similarly concluded that evidence remained insufficient to support or reject a causal relationship for those vaccines.

The full-text PDF of the Danish cohort study states: "We found no support for the hypothesis of increased risk for autism after MMR vaccination in a nationwide unselected population of Danish children; no support for the hypothesis of MMR vaccination triggering autism in susceptible subgroups characterized by environmental and familial risk factors; and no support for a clustering of autism cases in specific time periods after MMR vaccination." It reports 6,517 autism diagnoses during 5,025,754 person-years and a fully adjusted hazard ratio for autism of 0.93 (95% CI, 0.85–1.02) comparing MMR-vaccinated versus unvaccinated children.

In 1998, Andrew Wakefield and 12 of his colleagues published a case series in The Lancet that suggested the measles, mumps, and rubella (MMR) vaccine may predispose to behavioral regression and pervasive developmental disorder in children. The article later notes that The Lancet completely retracted the paper in February 2010 and that the editors stated the data were insufficient to establish any causal link between MMR vaccine and autism.

This 2014 meta-analysis in the journal Vaccine pooled data from case–control and cohort studies examining vaccines and autism spectrum disorder. The authors reported that "vaccinations are not associated with the development of autism or autism spectrum disorder" and that neither vaccine components such as thimerosal nor the MMR vaccine itself were linked to increased autism risk. The study concluded that "vaccination is not associated with the development of autism or autism spectrum disorder," based on the aggregated epidemiological evidence.

The guide notes that the original claim connecting autism and the MMR vaccine "was discredited in 2010 when the study was retracted" by The Lancet. It states that since then "hundreds of millions of dollars have been spent to investigate any potential link between vaccines and autism" and that "no environmental factor has been studied as extensively in as many people, and no link has been found between vaccines and autism—whether considering vaccine ingredients or the body's immune response to vaccines." It concludes that "the worldwide scientific consensus has been made clear: there is no link between vaccines and autism."

This BMJ news article describes an earlier Danish cohort study of 537,303 children born between January 1991 and December 1998, and notes: "A Danish study of more than half a million children showed no link between measles, mumps, and rubella (MMR) vaccination and autism." The authors of the original study found that "There was no increase in the risk of autistic disorder or other autistic-spectrum disorders among vaccinated children as compared with unvaccinated children (adjusted relative risk of autistic disorder, 0.92; 95% confidence interval, 0.68 to 1.24; adjusted relative risk of other autistic-spectrum disorders, 0.83; 95% confidence interval, 0.65 to 1.07)." A BMJ editor commented that the study "shows that there is no association between autism and MMR vaccination."

The Autism Science Foundation states plainly that "vaccines do not cause autism" and that "there is no correlation between autism and vaccines." It explains that this has been "confirmed through dozens of scientific studies examining different types of vaccines and different vaccine timing schedules." The organization further notes that studies of thimerosal, a mercury-based preservative, show that "the data show no relationship between vaccines, thimerosal and autism" and that studies of vaccination during pregnancy "have not been found to increase the risk of autism for the child."

Independent reviews by experts, including the Institute of Medicine, concluded that the epidemiologic evidence shows MMR vaccine does not cause autism. The page also states that the original 1998 study was retracted because it was the product of dishonest and irresponsible research, and that British authorities revoked Wakefield's license to practice medicine.

This peer-reviewed article concludes that "neither the MMR vaccine nor thimerosal-containing vaccines were associated with an increased risk of ASD, as confirmed by large-scale cohort and case-control studies." It reports that epidemiological evidence from different countries "does not support a causal relationship between childhood vaccination and autism spectrum disorders." The authors describe the vaccine–autism hypothesis as unsupported by the bulk of scientific data.

The article reports that The Lancet retracted the 1998 Wakefield paper in 2010. It quotes the journal saying that several elements of the paper were incorrect, contrary to the findings of an earlier investigation.

The Danish public health institute Statens Serum Institut reports on a new nationwide cohort study examining aluminum in childhood vaccines: "A new Danish study finds no association between aluminum in childhood vaccines and 50 different health conditions, including autism, asthma, and autoimmune diseases." It notes that by analyzing data from more than one million Danish children, researchers "found absolutely no indication that the very small amount of aluminum used in the childhood vaccination program increases the risk of 50 different health outcomes during childhood." The summary states that the study "found no increased risk of autism, asthma, or autoimmune diseases in vaccinated children."

This educational review states that "bad science and the lack of a scientific approach to autism have fueled conspiracy theories that blame vaccines" for rising autism diagnoses. It explains that subsequent research has "ruled out vaccines as a cause of autism" and that the observed increase in diagnoses is more likely due to factors such as improved recognition, broader diagnostic criteria, and greater public awareness. The article also notes that the notorious 1998 MMR–autism paper was based on only 12 children, lacked an unvaccinated control group, and was later retracted after serious misconduct was uncovered.

NIMH notes that the causes of autism spectrum disorder "are not fully understood" but that research suggests "a combination of genetic, biological, and environmental factors" is involved. It explicitly states that "there is no evidence that vaccines cause autism" and that concerns about a possible link "have been extensively studied and disproven." The publication also highlights that changes in diagnostic criteria and increased awareness have contributed to higher reported prevalence.

The Institute for Vaccine Safety at Johns Hopkins University reviews epidemiological studies on MMR vaccine, thimerosal, and simultaneous vaccination. It states that "the epidemiological evidence consistently shows no association between MMR vaccine, thimerosal in vaccines, or simultaneous vaccination and ASD" (autism spectrum disorder). The site also notes that multiple large population-based studies have found no increased risk of autism in vaccinated children compared with unvaccinated or differently vaccinated groups.

The Autism Science Foundation aggregates key scientific literature on vaccines and autism, including IOM reports and major epidemiologic studies. It highlights that researchers have "asked the autism vaccine question over two dozen times and each time we get the same response: no relationship." The page links to the 2014 meta-analysis "Vaccines are Not Associated with Autism" and other large cohort and case–control studies that collectively find no evidence that MMR, thimerosal-containing vaccines, or the overall schedule of early childhood vaccines cause autism.

This peer-reviewed article in Clinical Infectious Diseases reviews the history of the MMR–autism controversy and the scientific evidence addressing it. The authors describe numerous large epidemiologic studies that "have failed to find an association between MMR vaccination and autism" and discuss how the continued public belief in a link persists despite this evidence. They argue that opposition to vaccines in this context represents "vaccine nihilism" in the face of robust data showing no causal connection between MMR vaccination and autism.

A summary of the Danish aluminum-adsorbed vaccine cohort notes that researchers used Denmark’s nationwide registry of 1,224,176 children born from 1997 to 2018 and followed them through 2020. It reports that the study "found no link between aluminum-containing vaccines and a wide range of chronic health and behavioral conditions, including autism spectrum disorder." The article quotes the authors’ conclusion that "this nationwide cohort study did not find evidence supporting an increased risk for autoimmune, atopic or allergic, or neurodevelopmental disorders associated with early childhood exposure to aluminum-adsorbed vaccine."

Multiple large cohort and case-control studies published after 1998 found no association between MMR vaccination and autism, including studies in Denmark and the UK. These studies are widely cited in public health guidance as part of the evidence base against a causal link.