  The COVID-19 outbreak is asynchronous in US counties. Mitigating the COVID-19
transmission requires not only the state and federal level order of protective
measures such as social distancing and testing, but also public awareness of
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 use the
daily probability of contracting (PoC) SARS-CoV-2 for a susceptible individual
to quantify the risk of SARS-CoV-2 transmission in a community. We found that
shortening by $5\%$ 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
reducing infection and deaths by a 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 the public to better understand
the risk of contracting SARS-CoV-2 on each day.
