The diverse coalition of supporters of Health Secretary Robert Kennedy Jr. includes several anti-vaccine activists who have long spread debunked claims that immunizations are responsible. One challenge is that it’s hard to disentangle the effects of Tylenol use from the effects of high fevers during pregnancy. Trump also urged not giving Tylenol to young children, but scientists say that research indicates autism develops in the fetal brain. The theory is that some, not all, children with autism may not properly metabolize folate, Mandell said. Though anti-vaccine activists, including Kennedy, have long suggested a link between vaccines and autism, widespread scientific consensus and decades of studies have firmly concluded there isn’t one.