A new analysis released today by the World Health Organization’s (WHO’s) Global Advisory Committee on Vaccine Safety (GACVS) suggests that, based on the available evidence, there is no causal association between vaccines and autism spectrum disorders (ASD), reaffirming decades of evidence supporting the safety of childhood immunizations.

GACVS, an independent panel of international experts established in 1999, reviewed the findings during its November 27 meeting. The committee examined two claims: that thiomersal-containing vaccines are associated with an increased risk of ASD and that vaccines in general contribute to autism diagnoses.

The review drew on 31 primary research studies published from 2010 to August 2025 and including data from multiple countries. Across the studies, the committee found consistent evidence of vaccine safety in childhood and pregnancy and no evidence of a causal link with ASD.

No tie between aluminum adjuvants and autism

GACVS also evaluated the safety of vaccines containing aluminum adjuvants, which are used to enhance immune response. The review looked at studies conducted from 1999 through 2023, as well as a recent large-scale cohort study that used nationwide data from Denmark on children born from 1997 to 2018. The committee found no association between the trace amounts of aluminum in some vaccines and ASD.

Global childhood immunization efforts represent one of the greatest achievements in improving lives, livelihoods and the prosperity of societies.

The findings reaffirm previous GACVS conclusions issued in 2002, 2004, and 2012, all of which found no evidence linking the preservative thimerosal or aluminum in vaccines to autism.

The WHO urged national health authorities to align immunization policies with the latest scientific evidence, noting the profound global impact of vaccines. Over the past 50 years, childhood immunization programs have saved an estimated 154 million lives.

“Global childhood immunization efforts represent one of the greatest achievements in improving lives, livelihoods and the prosperity of societies,” noted the WHO in a statement about the analysis. 

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