Health and Human Services Director Robert F. Kennedy Jr. consistently calls for a comprehensive long-term cohort study comparing vaccinated vaccinated individuals to investigate vaccines, particularly those containing aluminum, with autism or other health issues. However, Denmark has already conducted research on equal or even larger scales for decades, using its national registration system to provide clear and robust answers. These findings systematically refute the reliable link between vaccines and autism.
Epidemiological Strength in Denmark: Civil Registration System
Denmark’s success in this study is not due to experimental magic, but due to its robust infrastructure. Founded in 1968, the Danish Civil Registration System (CRS) assigns all residents a unique 10-digit identification number. This figure promotes a seamless link between health and management registrations across the country, ensuring near-complete coverage and follow-up on birth, vaccination, diagnosis, movement, and death. This system serves as the backbone of high-quality epidemiological research.
Landmark Study 1: Madsen et al. (2002) – MMR and autism
In one of the earliest and most frequently cited studies, Madsen et al. (2002) used the Danish registry to track all children born between 1991 and 1998. In their analysis there was no association between the MMR (measles-munzulvera) vaccine and the outbreak of autism. This conclusion was quickly strengthened by medical commentary, increasing the reliability of the research.
Landmark Study 2: Hviid et al. (2019) – larger scale, no links yet
Recently, Hviid et al. (2019) expanded previous research by analyzing data from an astounding 657,461 Danish children born between 1999 and 2010. They considered family risk factors, the effects of other vaccines, and the timing of the autism diagnosis, and ultimately did not notice an increased risk associated with MMR vaccination. Their findings persisted across subgroups, including children at high risk for autism, and examined the timing of diagnosis compared to vaccination.
Thimerosal, aluminum, and autism: no connection
Thimerosal (Mercury-based preservative)**: In 1992, Denmark removed thimerosal from its childhood vaccine schedule. If Thimerosal was a causal factor in autism, the rate is expected to decrease. But they continued to rise, disproveing such connections. Further analysis of almost half a million children in Denmark confirmed that there is no dose-response relationship with autism. Aluminum (adjuvant)**: A 2025 Danish study involving 1.2 million children over 20 years examined 50 health conditions including autism, allergies and autoimmune disorders, and found no association with aluminum-containing vaccines. Despite Robert F. Kennedy Jr.’s request to withdraw the study, the Journal * Annals of Internal Medicine * rejected, citing the strong methodology of the research and data quality, and found no evidence of scientific misconduct.
Why Danish research undermines RFK Jr.’s claim
Population Size Analysis: These studies are based on a large representative sample that includes hundreds of thousands to over one million children over the long term.
High quality registry data: Universal identifiers allowed Denmark to achieve full tracking and minimal participant losses, setting gold standard in cohort design.
Consistent Null findings: Multiple studies failed to link MMR, thimerosal, or aluminum with autism. Post-vaccination subgroups, onset, or clustering do not show an increased risk.
Methodological Transparency: While RFK Jr. condemns these studies for obfuscation or bias, journal editors and authors counter these claims and provide clear explanations about privacy laws and research design.
Denmark is already working on the questions raised by RFK Jr. Vaccines do not cause autism. Decades of national registration data on MMR, thimerosal and aluminum show no causal. The argument for conducting new double-blind vaccination and non-vaccination studies overlooks substantial empirical evidence already available.
Policy debate and public debate will benefit more from acknowledging this reality rather than asserting unscientific fear. Denmark’s large, well-designed research exists as a powerful counterpoint to the myth of automated vaccines.
