Interregional SARS-CoV-2 spread from a single introduction outbreak in a meat-packing plant in northeast Iowa

SARS-CoV-2 spread has proven to be especially difficult to mitigate in high risk settings, including nursing homes, cruises, prisons and various industrial settings. Among industrial settings, meat processing facilities in the United States have experienced particularly challenging outbreaks. We have sequenced SARS-CoV-2 whole viral genomes from individuals testing positive in an integrated regional healthcare system serving 21 counties in southwestern Wisconsin, northeastern Iowa and southeastern Minnesota, providing an overview of SARS-CoV-2 introduction and spread in a region spanning multiple jurisdictions with differing mitigation policies. While most viral introductions we detected were contained with only minor transmission chains, a striking exception was an outbreak associated with a meatpacking plant in Postville, IA. In this case, a single viral introduction led to unrestrained spread within the facility, affecting many staff and members of their households. Importantly, by surveilling viral sequences from the surrounding counties, we have documented the spread of this SARS-CoV-2 substrain from this epicenter to individuals in 13 cities in 7 counties in Iowa, Wisconsin and Minnesota, a region spanning 185 square miles. This study highlights the regional public health consequences of failures to rapidly act to mitigate viral spread in a single industrial setting.