On September 8, 2025, President Trump posted a video to social media that promoted the widely discredited theory that vaccines cause autism. The decades-old video featured prominent anti-vaccine activists David Geier and his father, Dr. Mark Geier, whose medical license was suspended, discussing some of their anti-vaccine theories.
A White House official argued that the video was focused on the safety of thimerosal, a type of mercury that was removed from childhood vaccines in 2001 as a precaution. Despite multiple scientific studies showing no link between thimerosal and autism, anti-vaccine theorists claim otherwise.
In March, Health and Human Services (HHS) Secretary Robert F. Kennedy, Jr. appointed David Geier to the agency to work on a study examining the long-debunked link between vaccines and autism.