The World Health Organization is pushing back against vaccine misinformation with a firm message grounded in science.
After examining years of medical research, the agency confirmed that vaccines used during childhood are not connected to autism spectrum disorders.
According to the WHO, its Global Advisory Committee on Vaccine Safety conducted a fresh analysis of existing evidence and found no proof of a causal relationship between vaccines and autism. In its statement, the organization said the findings reinforce its long held position that vaccines do not contribute to the development of autism.
The review evaluated 31 scientific studies published over a 15 year span, with the most recent research assessed in August 2025.
The committee focused on vaccine safety outcomes in both children and pregnant individuals, concluding that the overall data supports the continued use of routine immunizations.
One major area of focus involved vaccines containing thiomersal, a preservative that has been repeatedly targeted by anti vaccine movements. The committee determined that vaccines with thiomersal show a strong safety record and found no credible evidence linking the ingredient to autism spectrum disorders.
Researchers also assessed vaccines that use aluminum based adjuvants, which help strengthen immune responses while allowing for smaller doses.
The WHO said its analysis found no association between aluminum adjuvanted vaccines and long term or systemic health conditions.
While two studies suggested a possible connection between aluminum adjuvanted vaccines and autism, the committee flagged both as unreliable due to serious design flaws and a high risk of bias. The WHO concluded that trace amounts of aluminum used in vaccines do not pose a risk for autism and remain safe for continued use.
This marks the fourth time the WHO has reviewed vaccine safety in relation to autism, with earlier assessments completed in 2002, 2004, and 2012.
Each review reached the same conclusion, that high quality scientific evidence does not support any link between vaccines and autism, regardless of ingredients.
The updated statement arrives as vaccine skepticism continues to grow in the United States. Public concern has intensified under the leadership of Health and Human Services Secretary Robert F. Kennedy Jr., who has a long history of questioning vaccine safety.
In November, the Centers for Disease Control altered language on its vaccines and autism webpage, suggesting that a definitive link had not been ruled out.
Despite the change, other sections of the CDC website still state that scientific studies consistently show no relationship between vaccines and autism.
By reaffirming its position, the WHO is signaling that decades of research remain clear and consistent. The organization stressed that vaccines continue to be a safe and essential part of protecting global health.
