New 24-Year Study of 1.2 Million Children Shows Vaccines Do Not Raise Risk of Autism

A new 24-year study tracking more than 1.2 million children found no link between aluminum-containing vaccines and a wide range of chronic health and behavioral conditions, including autism spectrum disorder. The results re-affirm long-standing scientific consensus while decisively undercutting a claim that has fueled vaccine hesitancy and shaped public debate for years.

Published in the Annals of Internal Medicine, the study used Denmark’s nationwide registry of people born from 1997 to 2018 to examine vaccine-related aluminum. The researchers followed health outcomes through 2020, extending into adolescence and early adulthood for many of the children studied. In total, they evaluated 50 specific diagnoses, including autism, ADHD, asthma, type 1 diabetes and epilepsy.

“This nationwide cohort study did not find evidence supporting an increased risk for autoimmune, atopic or allergic, or neurodevelopmental disorders associated with early childhood exposure to aluminum-adsorbed vaccine,” researchers concluded.

The findings are significant because misguided concerns about aluminum in childhood vaccines have influenced parental decisions and fueled calls to alter national immunization schedules. Despite these concerns not being supported by reputable clinical evidence, they have persisted and, in some cases, gained traction in policymaking and public discourse. Bloomberg recently reported the Advisory Committee on Immunization Practices could be asked to review the usage of aluminum-containing vaccines.

This study meets such concerns head-on through a dataset of powerful scale, rigor and duration.

Aluminum salts are added to many inactivated vaccines to strengthen the body’s immune response. Their safety has been reinforced by decades of clinical use. Still, speculation about cumulative exposure in infancy has persisted, often amplified online and occasionally echoed in regulatory hearings or legislative proposals.

This study tested that hypothesis using national health registry data. Researchers estimated total aluminum exposure from vaccines administered in the first 24 months of life. They adjusted for birth weight, maternal health history, socioeconomic status, and other potential confounders. Results were consistent across the population and across conditions.

While no single study answers every possible question, this one addresses a wide set of them with great precision. The sample is large (1,224,176 children born in Denmark between 1997 and 2018), the exposures are well defined, the outcomes are specific, and the follow-up spans decades. Together, these factors provide meaningful weight and a clear conclusion.

They also strengthen the foundation for responding to public doubt. The results support continued use of aluminum-adjuvanted vaccines as part of the routine pediatric schedule. They reinforce the broader body of evidence showing that the current immunization program protects children without introducing new risks.

At a time when vaccine confidence remains fragile, evidence of this scale offers reassurance grounded in data and helps anchor public conversation in findings that can be measured, tested and repeated.