Nursing home staff networks and COVID-19

Significance Nursing homes account for 40% of US COVID-related fatalities as of August 31, highlighting the urgent need to reduce SARS-CoV-2 transmission routes in these facilities. Our large-scale analysis of smartphone location data reports half a million individuals entering a nursing home following the March 13 federal ban on visitors. With 5.1% of these individuals entering two or more facilities, a nursing home snapshot network emerges. More connections, likely arising from contractors and staff working at multiple facilities, are highly predictive of COVID-19 cases, whereas traditional regulatory quality metrics are unimportant in predicting outbreak size. With an estimated 49% of nursing home cases attributable to cross-facility staff movement, attention to highly connected nursing facilities is warranted. Nursing homes and other long-term care facilities account for a disproportionate share of COVID-19 cases and fatalities worldwide. Outbreaks in US nursing homes have persisted despite nationwide visitor restrictions beginning in mid-March. An early report issued by the Centers for Disease Control and Prevention identified staff members working in multiple nursing homes as a likely source of spread from the Life Care Center in Kirkland, WA, to other skilled nursing facilities. The full extent of staff connections between nursing homes—and the role these connections serve in spreading a highly contagious respiratory infection—is currently unknown given the lack of centralized data on cross-facility employment. We perform a large-scale analysis of nursing home connections via shared staff and contractors using device-level geolocation data from 50 million smartphones, and find that 5.1% of smartphone users who visited a nursing home for at least 1 h also visited another facility during our 11-wk study period—even after visitor restrictions were imposed. We construct network measures of connectedness and estimate that nursing homes, on average, share connections with 7.1 other facilities. Traditional federal regulatory metrics of nursing home quality are unimportant in predicting outbreaks, consistent with recent research. Controlling for demographic and other factors, a home’s staff network connections and its centrality within the greater network strongly predict COVID-19 cases.