High-Quality Masks Reduce Covid-19 Infections and Death in the US

The objective is to evaluate the widespread adoption of masks on community transmission of SARS-CoV2. We employed an agent-based stochastic network simulation model and a variant of a SEIR disease model with one million agents in census tracts representing a population of 10.5 million. We evaluated scenarios with 25% to 90% mask-related reduction in viral transmission (mask efficacy). An individual wears a mask with a discrete probability values in [0-100%] (mask adherence). A mask order was initiated 3.5 months after the first confirmed case, with temporary state-wide distancing and voluntary quarantining of households. If 50% of the population wears masks that are 50% effective, this decreases the cumulative infection attack rate (CAR) by 27%, the peak prevalence by 54%, and the population mortality by 29%. If 90% wear masks that are 50% effective, this decreases the CAR by 38%, the peak prevalence by 75%, and the population mortality by 55%.