A World Health Organization (WHO) expert committee has again confirmed there is no causal link between vaccines and autism spectrum disorders, after reviewing the latest global evidence, the agency said. Meeting on 27 November, the WHO Global Advisory Committee on Vaccine Safety examined 31 major studies published between 2010 and August 2025, covering data from multiple countries and looking at vaccines in general, as well as those containing thiomersal, a preservative used in some multi-dose vials.
The committee said the new review “strongly supports the positive safety profile of vaccines used during childhood and pregnancy” and “confirms the absence of a causal link with autism spectrum disorders”, according to a WHO summary of the findings. Experts also revisited concerns about vaccines that contain very small amounts of aluminium salts, added to boost the immune response, drawing on research spanning more than two decades and a large Danish study that followed children born between 1997 and 2018.
Their conclusion: the evidence “shows no association between the trace amounts of aluminium used in some vaccines and ASD”, and these ingredients have been used safely for many decades. The group reaffirmed earlier conclusions issued in 2002, 2004 and 2012 that “vaccines, including those with thiomersal and/or aluminium, do not cause autism”.
WHO urged governments to keep vaccine policies anchored in science, noting that global childhood immunisation campaigns are “one of the greatest achievements” in improving health and prosperity. The agency estimates vaccines have saved at least 154 million lives over the past 50 years. The update follows a September statement responding to renewed political debate in the United States, where WHO warned against reviving discredited claims about vaccines and autism and stressed it will keep reviewing new evidence and advising countries based on the strongest available science.
