Vaccines and Autism: Clear Answers for Learners

Many people ask whether vaccines cause autism, and this question has been studied extensively. Large, high-quality studies have found no link between routine childhood vaccines and autism, and scientists have reviewed vaccine ingredients such as thimerosal. Although a small 1998 paper suggested a connection, that Lancet study was later retracted and its methods were discredited. While concerns remain in some groups, leading health organizations have confirmed the evidence does not support a causal link.

Research has shown that removing thimerosal from most childhood vaccines did not reduce autism rates, which argues against a causal role for this preservative. The World Health Organization issued a statement on 24 September 2025 noting that childhood vaccines do not cause autism. Therefore, public health experts continue to recommend following the routine immunization schedule to protect children and communities. However, people with questions should speak with their doctor to discuss vaccine timing and safety. A large Danish study of 657,461 children found no increased risk of autism after MMR vaccination. CDC and other national agencies continue to monitor vaccine safety using multiple surveillance systems. People deserve clear answers about safety.