Health secretary Robert F. Kennedy Jr. had previously said the U.S. would find the cause of autism by September.

Fox News senior medical analyst Dr. Marc Siegel outlines the key findings issued by HHS Secretary Robert F. Kennedy Jr.

HHS Secretary Robert F. Kennedy Jr. told CNN's Kaitlan Collins that it will "probably take another six months" to uncover the "most solid information" on autism causes during an interview on Thursday.

"We are seeing the proliferation of vaccine hesitancy, with a pronounced partisan split," a health expert told Newsweek.