A new poll from health research firm KFF reveals that US adults who frequently use artificial intelligence chatbots for health advice are more likely to believe anti-vaccine myths, including the debunked claim that vaccines cause autism.
Poll Findings on AI and Vaccine Misinformation
The survey, conducted in May 2025 with a representative sample of 2,480 US adults, found a strong correlation between frequent use of AI tools for health information and belief in falsehoods such as the MMR vaccine causing autism or mRNA vaccines altering DNA. This connection persisted even after controlling for factors like age, race, education, and political affiliation.
Among frequent AI users—those who seek health advice from chatbots at least once a week—35% believe it is “definitely or probably true” that MMR vaccines cause autism. In contrast, only 20% of non-AI users hold that belief, while 29% of occasional AI users agree.
Wider Implications of AI in Health Information
The findings raise concerns about AI's role in spreading misinformation. A previous KFF survey from March 2025 found that about one-third of US adults turn to AI for health advice. OpenAI has acknowledged this trend, stating in a January 2025 blog post that “health is already one of the most common ways people use ChatGPT, with hundreds of millions of people asking health and wellness questions each week.”
The poll also found that 29% of frequent AI users believe mRNA vaccines can change DNA, compared to 20% of non-users. Additionally, 22% of frequent AI users think the measles vaccine is more dangerous than the measles virus, versus 15% of non-users.
Social Media and Demographic Differences
Social media use also correlated with vaccine misinformation. Adults who use social media for health information weekly are more than twice as likely to believe the MMR-autism myth (37% vs. 16%). Demographically, lower-income groups and those without college degrees are more likely to seek health advice on social media, while higher-income and college-educated individuals prefer AI tools.
The KFF poll did not specify which AI models respondents used, noting that different chatbots vary in misinformation levels due to training data and company policies.
Historical Context of Vaccine Myths
The myth linking MMR vaccines to autism originated from a 1998 study in The Lancet, which was later retracted and debunked by numerous studies. The anti-vaccine movement has gained traction post-Covid-19, especially with Robert F. Kennedy Jr. as US health secretary.
Using chatbots for health information continues a pattern seen with search engines: about 5% of Google searches are health-related, and 77% of people use search engines for new diagnoses, according to a 2025 Georgetown University study.
