Lessons for future outbreaks from successful contact tracing systems in Asia.

Countries around the world had utilized contact tracing to support public health responses to curb transmission during the COVID-19 pandemic. In particular, countries in East and Southeast Asia had been effective in their contact tracing responses. To understand their successes, the contact tracing systems of Japan, Thailand, Singapore and Vietnam were comparatively analyzed, including the technical aspects of contact tracing approaches, detection and response structures. Through the comparative analysis, we uncovered the key elements within these successful systems, namely speed, capture and accuracy, designed specific for the countries' settings. For the system to work efficiently, we found that maintaining the balance across speed, capture and accuracy while adapting to the disease epidemiology and environment was essential. Contact tracing will remain a vital strategy to control the next epidemic with a pandemic potential. The lessons learnt could provide guiding principles to help enhance contact tracing systems and prepare for future outbreaks.