Abstract
The proliferation of misinformation within end-to-end encrypted messaging applications (EMAs) poses severe challenges to public health governance and digital communication integrity. Unlike open social media platforms, EMAs such as WhatsApp, Telegram, and Signal obscure content visibility, rendering automated moderation and public counter-messaging largely ineffective. This qualitative study investigates the socio-technical dynamics driving the dissemination, appraisal, and amplification of health misinformation within private messaging networks during public health crises. Drawing upon semi-structured in-depth interviews with 42 active EMA users across diverse demographic backgrounds, supplemented by digital artifact elicitation, this research unpacks the interpersonal mechanics of peer-to-peer transmission. The analysis reveals that forwarding behaviors are predominantly propelled by affective motivations, relational obligations, and perceived epistemic authority rather than intentional malice. Furthermore, algorithmic affordances such as friction-free forwarding mechanisms and group dynamics amplify confirmation bias and collective anxiety. Our findings indicate that digital health literacy interventions must transition from platform-level content policing toward interpersonal, community-situated epistemic toolkits. This study contributes to the socio-technical understanding of dark social spaces and provides actionable insights for digital public health communication, interface design, and policy development.