Most US adults either still mistakenly believe that Health and Human Services Secretary Robert F. Kennedy Jr. doesn’t recommend the measles, mumps, and rubella (MMR) vaccine or are unsure of his stance, prompting doubt about his ability to address ongoing measles outbreaks across the country, according to a poll released today by the Annenberg Public Policy Center (APPC) at the University of Pennsylvania.

In addition, most adults dismiss the Trump administration’s claim that childhood vaccines cause autism, and while half of poll respondents still hold the same unfavorable opinion of Kennedy they did in August 2025, significantly more say they view him very unfavorably.

Americans’ uncertainty of where Kennedy stands on the MMR vaccine might in large part be traced back to Kennedy himself. He has rarely provided unflinching support for the highly effective vaccine.

More than 1,900 adults responded to the poll, conducted from August 4 to 17. Of all participants, 31% correctly stated that Kennedy recommends the MMR vaccine, up from 23% in August 2025. But most indicated that Kennedy either doesn’t recommend the vaccine (29%) or are unclear about his position (40%).

“Measles is highly contagious,” APPC research analyst Laura Gibson, PhD, said in the news release. “As we’ve seen this year, communities that don’t maintain 95% vaccination rates are at risk for outbreaks.”

As of late last week, the Centers for Disease Control and Prevention (CDC) had confirmed 3,659 measles cases so far this year, compared with 2,289 for all of 2025. Nearly all of infected people (95%) were either unvaccinated or had an unknown vaccination status. 

Pennsylvania is still the nation’s hot spot, with 903 cases, 114 of them from the past week, including four deaths. While the CDC initially didn’t recognize any of the deaths, it now lists two.