Epidemiology reveals mask wearing by the public is crucial for COVID-19 control

Highlights • Epidemiology reveals mask wearing by the public is crucial for COVID-19 control • COVID-19 is mainly transmitted by saliva droplet which containing considerable copies of virus. Asymptomatic carriers are the main source of infection. • Under different public health policies, infection curve responded more sensitively than daily reported cases and reveals that wearing mask by the public is the most efficient way to reduce daily infection cases. • Our results elucidated the importance of daily infection curve in the assessment of efficiencies of prevention measures in an epidemic outbreak. • Mask wearing by the public will be an important policy during the lifting of lockdown, as continued wearing masks can help prevent the epidemic from spreading again. Abstract Objective The pandemic 2019 Coronavirus disease (COVID-19) is the greatest concern globally. Here we analyzed the epidemiological features of China, South Korea, Italy and Spain to find out the relationship of major public health events and epidemiological curves. Study design In this study we described and analyzed the epidemiological characteristics of COVID-19 in and outside China. We used GAM to generate the epidemiological curves and simulated infection curves with reported incubation period. Results The epidemiological curves derived from the GAM suggested that the infection curve can reflect the public health measurements sensitively. Under the massive actions token in China, the infection curve flattened at 23rd of January. While surprisingly, even before Wuhan lockdown and first level response of public emergency in Guangdong and Shanghai, those infection curve came to the reflection point both at 21st of January, which indicated the mask wearing by the public before 21st Jan were the key measure to cut off the transmission. In the countries outside China, infection curves also changed in response to measures, but its rate of decline was much smaller than the curve of China's. Conclusion The present analysis comparing the epidemiological curves in China, South Korea, Italy and Spain supports the importance of mask wearing by the public. Analysis of the infection curve helped to clarify the impact of important public health events, evaluate the efficiencies of prevention measures, and showed wearing masks in public resulted in significantly reduced daily infected cases.