Controversial vaccine skeptic Andrew Wakefield attended one of President Trump’s inaugural balls late Friday, prompting a flood of mostly negative reaction on social media, with many commenters raising concerns that his discredited ideas will gain traction in the new administration.

Wakefield, who helped launch the anti-vaccine movement with a fraudulent study linking vaccines to autism, posted a Periscope video from one of the balls, calling for an overhaul of the Centers for Disease Control and Prevention.