A new analysis by a World Health Organization (WHO) global expert committee has once again confirmed that childhood vaccines are not linked to autism spectrum disorders (ASD), reinforcing decades of scientific evidence supporting vaccine safety.

The findings come from the Global Advisory Committee on Vaccine Safety (GACVS), an independent group of international experts established in 1999 to advise WHO on key issues related to vaccine safety worldwide.

During a meeting held on November 27, 2025, the committee reviewed extensive research examining whether thiomersal-containing vaccines or any childhood vaccines contribute to autism. Their analysis included 31 primary studies published between 2010 and August 2025, covering data from multiple countries and diverse populations.

The conclusion was clear: there is no causal relationship between vaccines and ASD. The committee emphasized that vaccines used during pregnancy and childhood continue to demonstrate a strong safety profile.

The committee also evaluated long-standing concerns about aluminum-based adjuvants, ingredients used to strengthen the body’s immune response to vaccines. Reviewing studies from 1999 to 2023, including a major Danish cohort study tracking children born between 1997 and 2018, GACVS found no evidence connecting trace amounts of aluminum in vaccines to autism.

The findings uphold previous conclusions issued by GACVS in 2002, 2004 and 2012, which all stated unequivocally that thiomersal and aluminum-containing vaccines do not cause autism.

Following its review, WHO urged national health authorities to base their immunization policies on the strongest available science. The organization emphasized that vaccines remain one of the most impactful public health tools in history.

Over the past 50 years, global childhood immunization programs have saved an estimated 154 million lives, dramatically reducing deaths from diseases like measles, diphtheria, and polio.

As misinformation continues to fuel vaccine hesitancy worldwide, WHO’s latest reaffirmation sends a clear message: vaccines are safe, effective, and critical for protecting children’s health