The infodemic-pandemic nexus: Cross-national analysis of online misinformation's impact on population health.

The COVID-19 pandemic has been parallelled by an "infodemic" - a surge in both accurate and misleading information circulating online. This study examines whether engagement with digital mis- and disinformation contributes to cross-national variation in population health outcomes. Drawing on data from 31 countries over a three-year period, we integrate indicators of online misinformation exposure and COVID-19 case rates, controlling for vaccination uptake, civil protests against public health measures and policy stringency. Using a mixed-effects regression framework that accounts for smoothed time trends and country-specific factors and random effects, we find that greater public engagement with unreliable online content predicts significant future increases in new infection rates. Our findings offer one of the first multinational assessments of the pathways through which digital misinformation shapes real-world health outcomes. We argue that unequal responsiveness to online misinformation can generate divergent epidemic trajectories, underscoring the urgent need for policy interventions targeting the digital information environment.