Robust estimation of SARS-CoV-2 epidemic at US counties

The COVID-19 outbreak is asynchronous at US counties. Mitigating the COVID-19 transmission requires not only the state and federal level order of protection measures such as social distancing and testing, but also public's awareness of the time-dependent risk and reactions at county and community levels. We propose a robust approach to estimate the heterogeneous progression of SARS-CoV-2 at all US counties having no less than 2 COVID-19 associated deaths, and we develop the daily probability of contracting (PoC) SARS-CoV-2 for a susceptible individual to quantify the risk of SARS-CoV-2 transmission in community. We found that shortening only $5\%$ of the infectious period of SARS-CoV-2 can reduce around $39\%$ (or $78$K, $95\%$ CI: $[66$K $, 89$K $]$) of the COVID-19 associated deaths in the US as of 20 September 2020. Our findings also indicate that the reduction of infection and deaths by shortened infectious period is more pronounced for areas with the effective reproduction number close to 1, suggesting that testing should be used along with other mitigation measures, such as social distancing and facial mask wearing, to reduce the transmission rate. Our deliverable includes a dynamic county-level map for local officials to determine optimal policy responses, and for public to better understand the risk of contracting SARS-CoV-2 on each day.