Long before the COVID-19 pandemic, Robert F. Kennedy Jr. was building up a following with his anti-vaccine nonprofit group, Children’s Health Defense, and becoming one of the world’s most influential spreaders of fear and distrust around vaccines.

Now, President-elect Donald Trump says he will nominate Kennedy to lead the Department of Health and Human Services, which regulates vaccines.

Kennedy has long advanced the debunked idea that vaccines cause autism. He has also pushed other conspiracy theories, such as that COVID-19 could have been “ethnically targeted” to spare Ashkenazi Jews and Chinese people, comments he later said were taken out of context. He has repeatedly brought up the Holocaust when discussing vaccines and public health mandates.