“My child developed symptoms of autism after vaccination” — this is the most common phrase that psychiatrists hear while taking a medical history from the mother of a child suspected of having Autism Spectrum Disorder (ASD).
Although this myth emerged more than 20 years ago and numerous studies have since disproved any link between ASD and vaccination, the idea remains widespread. Unfortunately, this belief leads to serious consequences, including outbreaks of dangerous infectious diseases and even child mortality. Let us examine whether there is truly any correlation between vaccination and ASD, and where this belief originated.
WHY PARENTS BECOME CONCERNED
Autism Spectrum Disorder (ASD) is a neurodevelopmental condition that may cause significant social, communication, and behavioral difficulties.
ASD manifests during early development, typically in early childhood. Because of this timing, many parents notice the onset of symptoms around the same period as the childhood immunization schedule, leading them to perceive a connection.
Due to the rising prevalence of ASD in recent decades, both researchers and concerned parents have proposed various theories regarding its causes. This has drawn widespread public attention. Parents began asking:
“Is the increase in autism due to improved diagnostics?”
“…or is vaccination responsible for this rise?”
“If vaccines are not the cause, then what is?”
Let us address these questions, beginning with the vaccine that became the foundation of the anti-vaccination movement.
THE MMR VACCINE AND THE ORIGIN OF THE MYTH
The MMR vaccine is part of the routine childhood immunization schedule in the United States and many other countries. It is administered in two doses: the first at 12–15 months and the second at 4–6 years of age. It contains live attenuated viruses: measles, mumps, and rubella. The vaccine is generally well tolerated. The most common side effects are injection-site reactions, fever, and mild rash.
In the late 1990s, Andrew Wakefield, a physician at London’s Royal Free Hospital, published an article in The Lancet claiming that the attenuated measles virus in the MMR vaccine caused autism. He reported on 12 children who developed developmental delays shortly after receiving the MMR vaccine and proposed a new form of autism associated with vaccination. This publication caused widespread fear and distrust of vaccines.
Later investigations revealed major ethical violations, conflicts of interest, and falsified data. The Lancet formally retracted the article, and Wakefield lost his medical license.
THIMEROSAL AND MERCURY FEARS
Another argument supporting the myth involved thimerosal, a mercury-containing preservative once used in some vaccines. Although mercury is toxic at high doses, the form of mercury in thimerosal is eliminated rapidly from the body and has a favorable safety profile.
Nevertheless, due to public concern, thimerosal was removed from childhood vaccines in the U.S., EU, and many other countries by 2001. Extensive research has demonstrated no association between thimerosal and ASD or any neurodevelopmental disorders.
WHAT THE EVIDENCE SHOWS
Large-scale studies across multiple countries consistently demonstrate no causal relationship between MMR vaccination and autism, including:
• A 2019 nationwide Danish cohort study of 657,461 children
• A Danish retrospective cohort of 537,303 children
• The first large Asian case-control study
• A UK population study examining ASD rates before and after MMR introduction
All reached the same conclusion: vaccination does not increase the risk of ASD.
WHY VACCINES MATTER
Measles, mumps, and rubella are not benign infections.
Measles can cause pneumonia, encephalitis, seizures, blindness, and death.
Mumps may lead to meningitis, encephalitis, pancreatitis, and permanent deafness.
Rubella during pregnancy causes congenital rubella syndrome, resulting in miscarriage, blindness, deafness, and severe birth defects.
Ironically, vaccination has been so successful that many people now fear vaccine side effects more than the diseases themselves — leading to declining immunization rates and renewed outbreaks.
WHAT ACTUALLY CAUSES ASD
There is no single cause of autism. Instead, ASD arises from a complex interaction of risk factors, including:
• Genetic variants (over 100 genes implicated)
• Advanced paternal age
• Prenatal and perinatal brain injury
• Prematurity
Historical data also show that large rubella outbreaks (not vaccines) significantly increased autism rates, demonstrating that viral brain injury — not immunization — is the true risk.
Parents’ fear is deeply understandable when a child is diagnosed with ASD. Searching for causes is a natural response. Unfortunately, misinformation can easily mislead families, generate guilt, and undermine trust in healthcare.
For this reason, families deserve guidance from experienced, qualified professionals who provide reliable information, psychoeducation, and compassionate support while navigating this difficult path.