There is no evidence whatsoever linking the development of autism to childhood vaccines, research from the University of Sydney has shown.
The world-first analysis, published in the journal Vaccine, pooled all available studies on links between autism and vaccines for diphtheria, tetanus, whooping cough, as well as the MMR shot for measles, mumps and rubella.
The data covered more than 1.25 million children from the US, UK, Japan and Denmark, and found no risk of autism associated with any of the vaccines tested, or the ingredients they contain, including thimerosal and mercury.
"The findings were saying nothing. The odds ratio came up null, null, null. That means there's no connection," associate professor Guy Eslick, who led the research, said. "You can't get better than that."
"I hope it reaches a lot of parents who are sitting on the fence about whether to vaccinate their kids. I hope it helps to change their minds," Eslick said.
No industry funding was taken for the study.
Eslick said he hoped the findings would put the "final nail in the coffin" of the anti-vaccination movement, but said he understood if some parents whose children had developed autism would remain skeptical. "It's an emotional topic … they want reasons for why their child is the way they are, and the unfortunate thing is they'll cling onto misinformation and spurious studies."
Fears that childhood vaccines were linked to autism was sparked by a 1998 article co-written by Andrew Wakefield in the British journal the Lancet. The study was subsequently retracted and Wakefield was deemed to have acted "dishonestly and irresponsibly" in his research.
An Australian group that has campaigned against vaccinations was ordered last November to change its name from the Australian Vaccination Network to the Australian Vaccination-Skeptics Network after a tribunal ruled the original name was misleading.
The organization surrendered its charitable status in March after a New South Wales government probe found it was spreading information that was incorrect or presented in a "very selective manner".
Immunization coverage in Australia is generally high, but about 75,000 children are still not fully vaccinated. About 15,000 of these children have been registered by their parents as conscientious objectors.
Earlier this year the NSW government issued an "urgent reminder" to parents to vaccinate their children after ongoing measles outbreaks, including 26 cases up to the beginning of March.
This article originally appeared on guardian.co.uk