For the past 18 months, the vaccine landscape in the United States has been changing dramatically. And many changes are coming from the top. The U.S. Centers for Disease Control and Prevention altered its public stance on the possible relationship between vaccination and autism in November of last year. Previously, the agency tasked with ensuring the public health of the country and protecting the lives of all its people hewed toward the broad scientific consensus that there is no rigorous evidence that points to a causal or even a correlational link between vaccines and autism.
As of Nov. 19, 2025, the CDC states that: “The claim ‘vaccines do not cause autism’ is not an evidence-based claim because studies have not ruled out the possibility that infant vaccines cause autism.” Prior to that date, the CDC’s guidance claimed “that there is no link between receiving vaccines and developing autism spectrum disorder.”
This change of course from the nation’s top public health agency could have far reaching effects, including flagging vaccination rates. A team of European researchers set out to measure the impacts of the CDC’s communication shift on attitudes and perceptions in the U.S. In a Science paper published today, the scientists describe the results of an online survey they administered to more than 2,900 adults living in the U.S. To some of these respondents they showed what they called an “uncertainty-based message” currently being broadcast by the CDC. To others they served the older “consensus-based” CDC statement about the lack of scientific evidence for a relationship between vaccination and autism.
Their findings were stark. The study participants who received the uncertainty-based statement perceived higher risks of vaccine side effects and expressed greater uncertainty about vaccine safety than the people shown the consensus-based message. “Consistent with these perceptions, exposure to the uncertainty-based statement also reduced participants’ own vaccination intentions,” the authors added.
Read more: “Our Dark, Unvaccinated Future”
Remarkably, these changes in perception based on the flavor of message delivered to participants did not hinge on political affiliations. “This indicates that the consensus-based statement tends to mitigate uncertainty and promotes vaccination intentions, whereas the uncertainty-based statement has the opposite effect,” the study authors wrote.
As vaccine-related changes beyond communication strategies sweep through the CDC—this past June Health and Human Services Secretary Robert F. Kennedy Jr. replaced the agency’s 17-member Advisory Committee on Immunization Practices with people who had expressed anti-vaccine views similar to Kennedy’s—the vaccine landscape in the U.S. is looking very different than it did just a year ago. Earlier this year, the agency overhauled the childhood immunization schedule and deemphasized recommendations to get flu, COVID-19, and other vaccinations. “The CDC policy shift, in combination with potential changes in vaccination recommendations, could plausibly produce larger impacts than either change alone if their effects accumulate across repeated exposures and policy touchpoints,” the authors of the Science paper wrote. “Even modest declines in uptake, if sustained and population-wide, could translate into preventable illness, added strain on health systems, and higher public health costs.”
Meanwhile, another paper published this week highlighted the role of the polarized media landscape in encouraging vaccine hesitancy in the U.S. A trio of Johns Hopkins University researchers conducted another survey, with funding from pharmaceutical company Merck, asking more than 2,900 U.S. adults about their media consumption habits and their views on the measles, mumps, and rubella (MMR) vaccine that is recommended for children early in life. Published in the journal Vaccine, the results of the survey indicate that respondents who got their news from far-right media outlets, such as Britbart and Newsmax, were more than twice as likely to be vaccine hesitant. The researchers also reported that study participants who expressed vaccine hesitancy were more likely to consult non-authoritative information sources for their health guidance. These included social media health influencers and alternative health newsletters. Conversely, people who relied on guidance from physicians were most buffered from MMR vaccine hesitancy. “Media matters, not only in the health information that is presented, but also in what stories are not being presented,” the authors wrote. “In this analysis, general news media habits emerged as having the strongest associations with MMR hesitancy, specifically engagement with ‘new’ right media sources.”
This is set against a backdrop of a measles outbreak in South Carolina that sickened nearly 1,000 people, the worst seen in the country in more than 35 years. Last year, a similar measles outbreak in Texas affected more than 760 people and killed two children. 
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Lead image: Real Vector / Adobe Stock
