Effectiveness of non-pharmaceutical interventions on COVID-19 transmission in 190 countries from 23 January to 13 April 2020

Bo, Yacong; Guo, Cui; Lin, Changqing; Zeng, Yiqian; Li, Hao Bi; Zhang, Yumiao; Hossain, Md Shakhaoat; Chan, Jimmy W.M.; Yeung, David W.; Kwok, Kin-on; Wong, Samuel Y.S.; Lau, Alexis K.H.; Lao, Xiang Qian

BACKGROUND: To evaluate and compare the effectiveness of four types of non-pharmaceutical interventions (NPIs) in containing the time-varying effective reproduction number (Rt) of COVID-19. METHODS: This study included 1,908,197 confirmed COVID-19 cases from 190 countries between 23 January and 13 April 2020. The implemented NPIs were categorized into four types: mandatory face mask in public, isolation or quarantine, social distancing and traffic restriction (referred to as mandatory mask, quarantine, distancing, and traffic hereafter, respectively). RESULTS: The implementations of mandatory mask, quarantine, distancing and traffic were associated with changes (95%confidence interval, CI) of -15.14% (-21.79% to -7.93%), -11.40% (-13.66% to -9.07%), -42.94% (-44.24% to -41.60%) and -9.26% (-11.46% to -7.01%) in the Rt of COVID-19 compared with those without the implementation of the corresponding measures. Distancing and the simultaneous implementation of two or more types of NPIs seemed to be associated with a greater decrease in the Rt of COVID-19. CONCLUSION: Our study indicates that NPIs can significantly contain the COVID-19 pandemic. Distancing and the simultaneous implementation of two or more NPIs should be the strategic priorities for containing COVID-19.