Most American adults report having heard or read some false claims about measles or the measles, mumps, rubella (MMR) vaccine, according to a new poll out Wednesday. The big picture: Misinformation about the virus and its treatment remains prevalent, and many are uncertain of the truth as the U.S. grapples with persistent outbreaks. As of last week, some 800 confirmed cases were reported across 25 states, according to the Centers for Disease Control and Prevention.
- There have been two confirmed deaths from measles, while the death of a third person who tested positive for measles is under investigation, according to the CDC.
- All three were not vaccinated, according to state authorities. Two doses of the MMR vaccine are 97% effective against measles, the CDC says.
Driving the news: Around six in ten adults say they have heard of or read about the false link between autism and the MMR vaccine, according to KFF's new poll of 1,380 U.S. adults.
- One in three reported having read or heard the false claim that the measles vaccines are more dangerous than being infected with measles itself — a share that's climbed by 15 percentage points in the past year.
- One in five have read or heard the claim that Vitamin A can prevent measles infections.
- When it comes to the claims, some of which have been amplified by HHS Secretary Robert F. Kennedy Jr., less than 5% of adults say they think they're "definitely true."
Yes, but: At least half of adults reported being uncertain about whether the claims are true or false, saying each is either "probably true" or "probably false."
- The poll revealed partisan divides on the issue. For example, 35% of Republicans said it was "definitely" or "probably true" that the MMR vaccine has been proven to cause autism, compared to one in ten Democrats.
- Broadly, awareness of the rise in measles cases also differs across partisans, with Democrats (71%) being far more likely than Republicans (49%) to know measles cases are higher this year than in recent years.
Threat level: Among parents who say that at least one of the three false claims about measles is "definitely" or "probably true," 24% say they have delayed or skipped some vaccines for their kids, compared with 11% who say the claims are "probably" or "definitely false."
Zoom out: Kennedy has recently recommended people get the vaccine, saying it's the "most effective way to prevent the spread of measles."
- But the secretary has a history of sowing vaccine skepticism and has recently promoted unconventional therapies for the virus.
- He downplayed the threat earlier this year, describing a recent outbreak as "not unusual."
- Kennedy and President Trump have also floated a false tie between vaccines and autism — though the study that built the foundation for the anti-vaccine claim was thoroughly debunked, and several other studies have found that vaccines are not associated with autism spectrum disorder.
Context: The echoes of the COVID-19 pandemic still reverberate throughout American society, such as in lingering partisan distrust of public health institutions, crossing over into emerging public health challenges.
- However, large majorities of adults and parents were still very or somewhat confident the vaccines are safe in KFF's poll — though confidence was notably lower among Republicans.
Methodology: The survey was conducted April 8-15, 2025, online and by telephone among a nationally representative sample of 1,380 U.S. adults in English (1,322) and in Spanish (58). The margin of sampling error including the design effect for the full sample is ± 3 percentage points.
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