Dr. Siyu Chen is a Postdoctoral Fellow at the Jockey Club School of Public Health and Primary Care, The Chinese University of Hong Kong, and a former Visiting Research Scholar at Yale University. His research focuses on digital health and behavioral interventions, with a particular emphasis on HIV prevention and vaccination behaviors. He developed and evaluated an AI-driven HIV self-testing chatbot that provides real-time counseling and support, working closely with community organizations and at-risk populations. Dr. Chen has authored over 40 peer-reviewed publications, with several as first or co-first author in high-impact journals such as JAMA Network Open, BMC Medicine, Journal of Medical Internet Research, and Applied Psychology: Health & Wellbeing. Beyond his research, he contributes to the global academic community as a reviewer for over 50 international journals and research grants. His work has been recognized with competitive fellowships and scholarships supporting international research mobility and collaboration.