YouTube is taking down several video channels associated with high-profile anti-vaccine activists including Joseph Mercola and Robert F. Kennedy Jr., who experts say are partially responsible for helping seed the skepticism that's contributed to slowing vaccination rates across the country. As part of a new set of policies aimed at cutting down on anti-vaccine content on the Google-owned site, YouTube will ban any videos that claim that commonly used vaccines approved by health authorities are ineffective or dangerous. Mercola, an alternative medicine entrepreneur, and Kennedy, a lawyer and the son of Sen. Robert F. Kennedy who has been a face of the anti-vaccine movement for years, have both said in the past that they are not automatically against all vaccines, but believe information about the risks of vaccines is being suppressed. Facebook banned misinformation on all vaccines seven months ago, though the pages of both Mercola and Kennedy remain up on the social media site. Their Twitter accounts are active, too. In an email, Mercola said he was being censored. Kennedy also said he was being censored. "There is no instance in history when censorship and secrecy has advanced either democracy or public health," he said in an email. Social media companies have hired thousands of moderators and used high-tech image- and text-recognition algorithms to try to police misinformation. YouTube has removed over 133,000 videos for broadcasting coronavirus misinformation.