Is Autism Caused By Vaccines?

No. No, It is not. See Below.

The notion that autism or any other developmental delay was directly or indirectly caused by vaccines originated from a single, faulty, and now notoriously debunked journal article in 1998.

So let’s dive into the article that started it all regarding the suspicion that autism is caused by vaccines. You may know that in 1998 Andrew Wakefield published an article in the Lancet which described a link between the MMR vaccine to a Crohn’s-type GI illness, which he labeled enterocolitis, and then described a “regression” post-vaccine. This information was publicized quickly both by the media and certain medical professionals at the time; however, it was later discovered that the “study” only contained a sample size of 12 children, some of which were never formally diagnosed with ASD, with no control group, and alleged falsified medical records. Further, patients were recruited by a compensation lawyer through the Royal Free Hospital and Medical School in London, as part of an effort to file lawsuits against MMR manufacturers, and Wakefield did not disclose his conflicts of interest or compensation.

In reaction to the Wakefield article and the chatter of other misinformation proponents, in the beginning of the 2000’s, we saw the rise of what is now known as the “anti-vaxx movement.” These are parents and other individuals have expressed that they feel vaccines contain poison, are unnatural, and cause adverse neurodevelopment or neurological effects, largely stemming from distrust in government, scientists, and healthcare providers. And I should note that there certainly is a gray area here; vaccines in essence unnatural and man-made, and it is possible (though rare) to have a negative reaction to a vaccine. However, what is abundantly clear is that the benefits of vaccines significantly outweigh the potential costs, both on an individual and societal level, as is the same for most of western medicine.

In the years following the Wakefield article, there was a significant increase of adverse vaccination reports (most unfounded); however, the reporting of adverse effects for other vaccines (e.g., HepB) remained consistent during the same time period. Coverage decreased from 92% to 80% from 2003 to 2004 in UK alone, continue to remain lower than recommended levels. In 2004, there was a short retraction by 10 of the 12 original authors; however, it wasn’t publicized and the anti-vaxx movement continued to grow. By 2008 there were measles outbreaks in the UK and US, resulting in the highest number of cases since early 90s. Measles cases then increased in USA and Canada in 2009. In 2010, the Lancet published a retraction stating that article was “utterly false” and as a result Wakefield lost his medical license but still, this didn’t appear to change much. Wakefield was still collaborating with celebrities like Jenny McCarthy stating that autism is caused by MMR vaccine. By 2011 more than 15 states in US dropped below 90% immunization and by 2015 there were 667 cases. In 2019 there were 1,282 cases in the US, most cases among unvaccinated youth, with similar patterns for other illnesses for which parents choose not to vaccinate for (e.g., whooping cough, mumps). Per a survey from 2021, almost 1/3 Americans believed that childhood vaccines may cause autism and as of 2022, and more than half of US states fall below the CDC recommended vaccination levels for MMR. In present day, as of June 2025, there are 1,127 cases of measles in the US. And the controversy continues. Recently, in Jan 2025, there was an article circulating that claimed an association between vaccines and neurodevelopment disorders; however, the research was purely observational in nature (based on billing claims database with high likelihood of coding errors/misclassification), was limited to low SES, largely African American children on medicaid in Florida state, included several diagnoses aside from autism, and those who were unvaxxed may have ASD but never diagnosed due to lack of follow up. There has been significant time and money wasted on exposing the fraud and debunking claims regarding vaccines and autism. Moreover, statements from CDC, American Academy of Pediatrics (AAP), National Health Service (NHS), and WHO stating no evidence linking MMR vaccine and autism, No studies able to replicate any link. Importantly, energy, time, and money have been diverted away from curing other diseases and therapies/services for autism to find a cure for autism and to treat new measles outbreaks.

13 studies from 1999 through 2006 failed to show a causal relationship between the MMR vaccine and autism (MMR, thimerosal, and combination). In one study, rhesus monkeys did not exhibit any behavioral or neurological differences between groups who receive vaccine and those who did not. As such, the mercury (AKA thimerasol) in vaccines has been demonstrated time and time again for the past 20 years to have no correlation with autism or any other developmental delay or cognitive disorder. Across several meta-analyses, it has been demonstrated that there is no association between thimerosal (in vaccines) and ASD. Of note, ASD symptomatology often appears around the same time period as vaccines are administered to infants and toddlers, so it is easy for one to mistakenly believe there is a correlation, where there is not. In fact, in 2008, the CDC stated on the their website based upon independent research, “There is evidence against the association of autism with persistent measles virus RNA in GI tract or MMR exposure.”

So how can we keep ourselves informed and dedicate care and attention to those who really need it? We need to disrupt negative vaccine associations by reducing exposure to false scientific/medical information on social media. Two of the big factors affecting vaccination status were found to be education and social media use. It is important that clinicians and others with a platform promote accurate information regarding causes and treatment (e.g., early intervention, diagnostic assessment, medication consult). Higher rates of vaccine exemption in a community are associated with greater measles incidence in the community, for both exempt and nonexempt populations. It is also recommended that media work in consultation with researches and public health workers to vet any vaccine-related story before sharing with the public for these reasons, as misinformation spreads like wildfire and we have to consider public safety with any information shared.