The influence of mask use on the spread of COVID-19 during pandemic in New York City

In New York City, the situation of COVID-19 is so serious that it has caused hundreds of thousands of people to be infected due to its strong infectivity. The desired effect of wearing masks by the public is not ideal, though increasingly recommended by the WHO. In order to reveal the potential effect of mask use, we posed a dynamical model with the effective coverage of wearing face masks to assess the impact of mask use on the COVID-19 transmission. We obtained the basic reproduction number R-0 which determined the global dynamics. According to the implement of policies in New York City, we divided the transmission of COVID-19 in three stages. Based on mathematical model and data, we obtain the mean value R-0 = 1.822 in the first stage of New York City, while R-0 = 0.6483 in the second stage due to that the US Centers for Disease Control and Prevention (CDC) recommended the public wear masks on April 3, 2020, R-0 = 1.024 in the third stage after reopening. It was found that if the effective coverage rate of mask use alpha exceed a certain value alpha(c) = 0.182, COVID-19 can be well controlled in the second stage of New York City. Additionally, when the effective coverage of masks reaches a certain level alpha = 0.5, the benefits are not obvious with the increased coverage rate compared to the cost of medical resources. Moreover, if the effective coverage of mask use in public reaches 20% in the first stage, then the cumulative confirmed cases will be reduced about 50% by 03 April, 2020. Our results demonstrated a new insight on the effect of mask use in controlling the transmission of COVID-19.