When Deepfakes Meet Herd Immunity: Artificial Intelligence, Vaccine Avoidance, and the Next Infodemic Threat.

Vaccination remains among the most effective public health interventions, but its impact increasingly depends on public trust and a reliable information environment. During the coronavirus disease 2019 (COVID-19) pandemic, misinformation became a major obstacle to vaccine uptake and disease control. The rapid development of generative artificial intelligence (AI)-including synthetic text generators, conversational chatbots, deepfake images, synthetic audio, and AI-generated videos-has changed how misinformation can be produced, personalized, and disseminated. This Perspective argues that AI-generated misinformation may represent a new stage in the evolution of the infodemic. Compared with earlier forms of vaccine misinformation, AI-generated content can be produced automatically, tailored to individual audiences, made visually persuasive, and distributed at unprecedented speed and scale. Drawing on historical vaccine controversies, health communication research, and epidemiological principles of herd immunity, we propose that AI-driven misinformation should be examined not only as a communication problem but also as a potential epidemiological risk factor that may weaken population immunity. The implications extend beyond vaccine hesitancy to the preparedness and resilience of public health systems during future pandemics. We discuss how anti-vaccination movements may change in the AI era and propose responses centered on trust-building, digital health literacy, information surveillance, and community engagement to support vaccine confidence and pandemic preparedness.