Achieving COVID-19 zero without lockdown, January 2020 to March 2022: The Taiwan model explained.

Despite never imposing a lockdown, Taiwan achieved COVID-19 zero, with reporting only 56 local coronavirus disease 2019 (COVID-19) cases after testing 126,987 individuals in 2020, and further contained a large outbreak rapidly and successfully in 2021. At the onset of the COVID-19 pandemic, our infectious disease modeling results indicated that testing and contact tracing alone would fail to contain the pandemic. However, by supplementing this approach with general public surgical mask-wearing, the reproduction number (R0) could be suppressed to less than 1. This would effectively contain the virus's spread within Taiwan, particularly when combined with strict border control measures to prevent the overwhelming influx of imported COVID-19 cases and ensure the capacity of the medical and public health systems remains resilient. These modeling results became the theoretical basis behind the highly successful Taiwan model against COVID-19 during 2020-2021, supporting by negative excess mortality, seroepidemiological surveys, and molecular epidemiological analyses. This is a public health triumph demonstrating that a democratic and humane approach to the COVID-19 pandemic is not only feasible but highly effective. It also highlights the crucial role of infectious disease modeling in assisting the formulation of a successful national pandemic response.