A large international research team led by the University of Vienna reports that changes in how the U.S. Centers for Disease Control and Prevention (CDC) communicates about vaccines and autism may significantly influence public attitudes toward vaccination. The findings, published in the journal Science, suggest that emphasizing uncertainty around a well-established scientific consensus can have measurable downstream effects on trust and behavioral intentions.
The widely accepted scientific consensus is that vaccinations are neither causally nor statistically linked to autism. However, the study focuses on a CDC website revision introduced under political pressure that shifted messaging from a clear statement of no association to language highlighting uncertainty and the need for further research.
Study design and approach
Researchers conducted a large-scale online experiment involving 2,989 US adults. Participants were randomly assigned to view one of three versions of CDC information: the previous statement affirming no link between vaccines and autism, the revised statement emphasizing uncertainty, or no statement (control group).
The goal was to assess how variations in authoritative health messaging influence perceptions of vaccine safety, trust in institutions, and vaccination intent.
Impacts on perception and intention
Participants exposed to the revised CDC wording reported greater perceived likelihood of vaccine side effects and increased concerns about vaccine safety. They also demonstrated lower intentions to receive vaccinations compared with those who viewed the earlier, consensus-aligned messaging or the control condition.
“Our study shows that the way information is communicated can itself be a risk factor,” said psychologist Alina Schneider of the University of Vienna. “It is not a question of concealing scientific uncertainty as a matter of principle. What is crucial is that it is communicated in a way that is consistent with the actual evidence—particularly on topics where there is already broad scientific consensus,” added Cornelia Betsch of the University of Erfurt and the Bernhard Nocht Institute for Tropical Medicine.
Trust and broader societal effects
Beyond vaccination intent, the study found that revised messaging reduced trust in the CDC and increased endorsement of science denialist thinking patterns, including selective use of evidence and conspiracy-like reasoning.
Researchers warn that even modest declines in vaccination uptake could contribute to increased preventable disease burden and higher healthcare costs. Lau Lilleholt of the University of Copenhagen noted that sustained reductions in vaccination rates may have significant public health consequences.
Implications for health communication
The authors argue that authoritative health communications should be carefully aligned with established evidence, transparently documented, and ideally tested for public interpretation before release. When uncertainty must be communicated, they emphasize the importance of clearly contextualizing it within the broader scientific consensus.
Study lead Robert Böhm of the University of Vienna stated, “When uncertainty is communicated, this should always be accompanied by a transparent contextualization within the overall state of research and a clear recommendation for action.”
Overall, the findings suggest that even subtle shifts in wording by trusted health authorities can meaningfully shape public perceptions, trust, and intended health behaviors.
Note: This news summary was generated by AI based on a published press release, followed by a review from human editors.
