Trump – who has previously said Kennedy would “go crazy” on health – said his health secretary would not “completely reinvent the wheel”.
He added: “He will not upset any system.”
But on autism, he continued: “Someone has to find out. If you go back 25 years ago, you had very little autism. Now you have it.
“When you’re talking about autism, because it’s been brought up, and you look at the amount we have today compared to 20 or 25 years ago, it’s pretty scary.”
Scientists have attributed the increase in autism diagnoses to improved screening methods, while saying it is caused by a complex mix of factors including genetics, environment and conditions during pregnancy and birth.