Evaluating the effects of case- and population-based interventions on COVID-19 containment in Taiwan: a mathematical modelling study

Abstract

Backgrounds Taiwan was one of the few countries with initial success in COVID-19 control without strict lockdown or school closure, and reasons for the success was worth being fully elucidated. Methods We adapted a stochastic branching process model with two-stage calibration to evaluate and compare the effectiveness of case-based (including contact tracing and quarantine) and population-based interventions (including social distancing and face mask use). The model was fitted to empirical case data in Taiwan to estimate the effective reproduction number under case-based interventions, population-based interventions, and both, assuming that the counterfactual reproduction number without any interventions was 2–3. Results After model calibration, we estimated that 52% (95% CrI 39–67%) of transmission events occurred during the pre-symptomatic stage. Case detection, contact tracing, and 14-day quarantine of close contacts (regardless of symptoms) would have decreased the reproduction number from the counterfactual value of 2·50 to 1·53 (95% CrI 1·50–1·57) and was not sufficient for epidemic control. The voluntary population-based interventions had a larger impact than case-based interventions, and would have reduced the reproduction number to 1.30 (95% CrI 1.03–1.58). Combining both case-based and population-based interventions would have the largest impact on the reproduction number (0·85 [95% CrI 0·78–0·89]). Interpretation Case-based interventions alone would be insufficient to contain the COVID-19 epidemic, even in a setting with a highly efficient contact tracing program. Our analysis of Taiwan’s success highlights that coordinated efforts from both government and citizens are indispensable in the fight against COVID-19 pandemic.