David A. Geier

David Geier is an American anti-vaccine activist. He is the son of fellow anti-vaccine activist Mark Geier. In 2025, he was hired by United States Secretary of Health and Human Services Robert F. Kennedy Jr. to search for evidence that federal officials had hidden information that supports the claim that vaccines cause autism.

Early life and education Geier's parents are Mark Geier and Anne Geier. He grew up learning science from his father and tennis from both parents. He attended the University of Maryland, Baltimore County starting in 1998; he received a B.A. in biology, and has taken graduate courses, but does not have any graduate degrees.

Career David followed in his father Mark Geier's footsteps in advocating against vaccines, particularly thiomersal, and promoting treatment of autism with chelation and Lupron shots. He was fined by the Maryland Board of Physicians for practicing medicine without a license in 2011.

In March 2025, Geier was appointed by Robert F. Kennedy Jr., who said Geier was intended to examine CDC vaccine safety data. Geier and his father had previously accessed this data and then been barred for misrepresenting his plans. The Intelligencer reported that inside sources think he will try to repeat a study that showed a statistically insignificant link between infant vaccines and neurodevelopmental disorders.