What about autism?

Key facts

  • A number of high-quality studies have confirmed that vaccination does not cause autism.

  • Elements of the research paper that raised the possibility of a connection between vaccination and autism (published in 1998) were found to be false. The medical journal in which the research was published has printed an apology and retracted the paper.

  • Current research suggests that autism is probably due to a combination of developmental, genetic and environmental factors.

Last updated on 10 September 2025.

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Overview

Many large studies have found that vaccines do not cause autism. The idea that vaccination caused autism was appealing to some people who wanted to find a clear cause. However, this idea arose from a few studies that were badly conducted and have since been proven wrong and fraudulent. Current research suggests that autism cannot be explained by a single cause, but is probably due to a combination of developmental, genetic and environmental factors.

How do we know that vaccines do not cause autism?

A number of high-quality studies have compared the health of large numbers of vaccinated and unvaccinated children over many years.1,2,3 One of the largest studies, which included 657,461 children born in Denmark, found that unvaccinated children were just as likely to develop autism as vaccinated children.4 When the results of several studies were combined to include medical information from nearly 1.5 million children living all around the world, researchers were able to confirm that vaccination could not be causing autism.5

Why do some people believe there is a connection?

Some people think there is a connection because a British research group, led by discredited researcher Andrew Wakefield, suggested that some children who had received the measles-mumps-rubella (MMR) vaccine went on to develop bowel disease and developmental disorders such as autism.6 The results of the research were published in a respected medical journal (The Lancet) in 1998. However, concerns about the paper were soon raised and the research was discredited because the results were based on a very small group of only 12 children and the data were found to be falsified and misleading. Wakefield had also failed to disclose two serious conflicts of interest.7 

In 2004, 10 of the original 12 co-authors retracted their claim that there was any association between vaccination and autism.8 The Lancet journal also published a retraction and apology after the General Medical Council found results reported in the paper had ‘proven to be false’.9

After it became clear that the MMR vaccine did not cause autism, some people suggested a preservative sometimes used in vaccines packaged in multi-dose containers might be linked to autism. This preservative, called thiomersal, is a salt that contains a tiny amount of mercury. The mercury salt in thiomersal (ethylmercury) is not like the mercury compound (methylmercury) that can build up in the human body.

None of the vaccines normally given to children in Australia are packaged in multi-dose containers, so none of them contain thiomersal or any other form of mercury. Thiomersal is still used in some other parts of the world where single- dose packages are too expensive or costly to transport. However, thiomersal is still safe and effective as a preservative. Several large studies have also compared the risk of autism in children who received vaccines containing thiomersal to those who received vaccines without thiomersal. The results of these studies demonstrate there is no causal relationship between vaccines that contain thiomersal and autism.5,10,11 

Can I get my child separate vaccines for measles, mumps, rubella vaccines?

You can’t get separate vaccines for measles, mumps, and rubella for your child because they are not available in Australia. Medical researchers are confident that vaccines don’t cause autism.12

  1. Madsen KM, Hviid A, Vestergaard M, et al. A population-based study of measles, mumps, and rubella vaccination and autism. New England Journal of Medicine 2002;347:1477-82 https://www.nejm.org/doi/10.1056/NEJMoa021134?url_ver=Z39.88-2003&rfr_id=ori%3Arid%3Acrossref.org&rfr_dat=cr_pub%3Dwww.ncbi.nlm.nih.gov
  2. Jain A, Marshall J, Buikema A, et al. Autism occurrence by MMR vaccine status among US children with older siblings with and without autism. JAMA 2015;313:1534-40. http://dx.doi.org/10.1001/jama.2015.3077
  3. Maglione MA, Das L, Raaen L, et al. Safety of vaccines used for routine immunization of US children: a systematic review. Pediatrics. 2014 Aug 1;134(2):325-37. https://doi.org/10.1542/peds.2014-1079
  4. Hviid A, Hansen JV, Frisch M, et al. Measles, mumps, rubella vaccination and autism: A nationwide cohort study. Annal of Internal Medicine 2019;170:513-20. https://doi.org/10.7326/M18-2101  
  5. Taylor, LE, Swerdfeger AL & Eslick GD. Vaccines are not associated with autism; an evidenced-based meta-analysis of case- control and cohort studies. Vaccine 2014;32:3623-3629. https://doi.org/10.1016/j.vaccine.2014.04.085
  6. Wakefield AJ, Murch SH, Anthony A, et al. RETRACTED: Ileal-lymphoid-nodular hyperplasia, non-specific colitis, and pervasive developmental disorder in children. The Lancet 1998;351:637-41
  7. Deer BN. How the case against the MMR vaccine was fixed. BMJ 2011;342-c5347. https://doi.org/10.1136/bmj.c5347  
  8. Murch SH, Anthony A, Casson DH, et al. Retraction of an interpretation. The Lancet 2004;363:750. https://doi.org/10.1016/S0140-6736(04)15715-2  
  9. The Editors of The Lancet. RETRACTED: Ileal-lymphoid-nodular hyperplasia, non-specific colitis and pervasive developmental disorder in children. The Lancet 2010;375:445. https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(10)60175-4/fulltext
  10. Fombonne E, Zakarian R, Bennett A, et al. Pervasive developmental disorder in Montreal, Quebec, Canada: Prevalence and links with immunisations. Pediatrics 2006;118:139-50. https://doi.org/10.1542/peds.2005-2993
  11. Hviid A, Stellfeld M, Wohlfahrt J, et al. Association between thimerosal-containing vaccine and autism. JAMA 2003;390:1763-66. https://doi.org/10.1001/jama.290.13.1763
  12. Gulati S, Sharawat IK, Panda PK, et al. The vaccine–autism connection: no link, still debate and we are failing to learn the lessons. Autism 2025;29:1639-45. https://doi.org/10.1177/13623613251345281