16-07-2025
Why myths around vaccines and autism are so persistent
Another major study has confirmed that routine childhood vaccines do not cause autism.
The theory emerged three decades ago and caught fire after a study was published – and later retracted – in a major medical journal in 1998. While the theory has since been discredited in many studies from around the world, the myth still persists.
Today, anti-vaccine activists often point to aluminium, which is used in trace amounts in many childhood jabs to increase their effectiveness, to argue that the vaccines are unsafe.
Danish researchers investigated this in the latest study, which was published in the Annals of Internal Medicine and included more than one million children born in Denmark between 1997 and 2018.
It found that aluminium-containing vaccines do not raise the risk of health issues such as autism spectrum disorder, asthma, or autoimmune disorders.
Dr Niklas Andersson, one of the study's authors and a vaccine researcher at Denmark's Statens Serum Institut (SSI), described the results as 'reassuring'.
'We have not found anything that indicates that the very small amount of aluminium used in the childhood vaccination programme increases the risk of 50 different health conditions in childhood," Andersson said in a statement.
The researchers said the findings should be used to dispel misinformation about vaccines, which have become a political flashpoint in recent years, including during the COVID-19 pandemic.
Health authorities blame these falsehoods for driving an increase in the number of parents who opt out of routine vaccines, leaving an opening for preventable diseases such as measles and whooping cough to make a comeback in Europe and elsewhere.
Since 2010, vaccine coverage has fallen for at least one jab in Austria, Belgium, Cyprus, Finland, France, Germany, Greece, Italy, Luxembourg, the Netherlands, Spain, Sweden, and the United Kingdom.
Why the myth sticks around
The theory that vaccines cause autism gained ground in the early 2000s, after the British doctor Andrew Wakefield published an article in The Lancet, a leading medical journal, in 1998 speculating that the measles, mumps, and rubella (MMR) vaccine may cause autism.
The study was full of methodological flaws and falsified data, and was later retracted. Wakefield, who made money from lawsuits filed against vaccine manufacturers, was also stripped of his medical license.
But his ideas were compelling to parents who noticed that their children received the MMR vaccine around the same time they began showing signs of autism.
Later studies went on to show that this was effectively a coincidence. While all vaccines come with some risk of side effects, routine childhood jabs are safe and effective – and do not raise the risk of autism, these studies concluded.
The myth has stuck around, though, partly because much is still unknown about what actually causes autism, and because diagnoses have risen since the turn of the century.
Scientists believe the uptick is due partly to increased awareness around autism and a wider definition of the disorder. They have also been researching whether environmental factors, such as prenatal exposure to air pollution or certain pesticides, may play a role.
In April, US health secretary Robert F Kennedy Jr pledged to identify what causes autism by September as part of a massive research project. Kennedy said scientists would assess the food system, the environment, parenting approaches, and vaccines, in a move widely panned by independent researchers.
Anders Hviid, a vaccine researcher at SSI, said large studies like the recent Danish report 'are part of the bulwark against the politicisation of health knowledge, which can damage trust in vaccines'.
'It is absolutely crucial that we clearly separate real science from politically motivated campaigns – otherwise we risk that it is Danish children who pay the price,' Hviid said.
