“Vaccines DO NOT cause autism”

Senator Cassidy wrote that vaccines "DO NOT cause autism". The World Health Organization's Global Advisory Committee on Vaccine Safety reviewed the research published between January 2010 and August 2025, 31 studies from several countries, and in December 2025 reaffirmed its earlier conclusions from 2002, 2004 and 2012: vaccines, including those containing thiomersal or aluminium, do not cause autism. One of the largest studies, published in Annals of Internal Medicine in 2025, followed more than 1.2 million children born in Denmark between 1997 and 2018 and found no link between aluminium-containing childhood vaccines and autism or any of 49 other chronic conditions. In November 2025 the CDC, under Health Secretary Robert F. Kennedy Jr., changed its vaccine safety page to call "vaccines do not cause autism" not an evidence-based claim, arguing that studies have not ruled out a link for infant vaccines; the American Academy of Pediatrics and the WHO disagreed. That change did not add new evidence. On the research available, the claim is true.