Meeting on November 27, the WHO Global Advisory Committee on Vaccine Safety reviewed 31 major research studies published between 2010 and August 2025.
The analysis covered data from several countries and looked at both vaccines in general and those containing thiomersal, a preservative sometimes used to prevent contamination in multidose vials.
‘Positive safety profile’
According to the committee, the latest 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”.
Experts also reviewed concerns about certain vaccines that contain very small amounts of aluminum salts, which help the body create a stronger immune response.
This assessment was based on studies published over more than two decades, as well as a large national study from Denmark that followed children born between 1997 and 2018.
The WHO committee concluded that the evidence “does not show any association between traces of aluminum used in some vaccines and ASD,” noting that these ingredients have been used safely for many decades.
Following the review, the group reaffirmed previous conclusions issued in 2002, 2004 and 2012: “Vaccines, including those containing thiomersal and/or aluminum, do not cause autism.”
The WHO urged governments to ensure vaccine policies remain rooted in science, noting that “global childhood immunization efforts represent one of the greatest achievements in improving lives, livelihoods and the prosperity of societies.”
In the last 50 years, the WHO estimates that vaccines have saved at least 154 million lives.
Debate in the United States
The update follows a WHO statement issued on September 24, following renewed political debate in the United States. That statement warned against the resurgence of debunked theories linking vaccines to autism, emphasizing that “there is a strong and extensive evidence base showing that childhood vaccines do not cause autism.”
Studies suggesting otherwise, the WHO said at the time, were wrong and have long been debunked.
The WHO reiterated that decades of independent research reaches the same conclusion: vaccines are safe, effective and essential for public health.
The organization said it will continue to review emerging evidence and advise countries based on the strongest science available.
