Enlarge / An MMR and VAR vaccine ready for a pediatric vaccination at Kaiser Permanente East Medical offices in Denver in 2015. (credit: Getty | Joe Amon)

For years, the US Centers for Disease Control and Prevention has bluntly stated the truth: "Vaccines do not cause autism," the agency affirms on its website. Yet, nearly a quarter of Americans still don't believe it.

In an April 2024 survey by the Annenberg Public Policy Center (APPC) of the University of Pennsylvania, 24 percent of US adults denied or disputed that the CDC ever said that. Specifically, the survey asked them to assess the accuracy of the statement that the CDC has said there is no evidence linking vaccines to autism. Six percent called the statement "very inaccurate," and 18 percent said it was "somewhat inaccurate." An additional 3 percent responded that they were "not sure." Of the remaining 73 percent, only 41 percent considered it "very accurate," and 32 percent said it was "somewhat accurate."

The results are largely unchanged from responses in 2018 when survey respondents were asked the same question. In that year, 26 percent of adults reported that the statement was "very inaccurate" or "somewhat inaccurate."