Study population and setting
Investigators aggregated nursing home resident COVID-19 case data reported to 23 state health departments in the United States through May 31, 2020. Geolocation smartphone data from March 13 to April 23, 2020 were mapped onto COVID-19 case reports to identify mobility patterns among staff, contractors, and residents across 6,644 nursing homes. Adjusting for compositional characteristics of nursing homes (e.g., demographic factors, quality measures), the investigators assessed the relationship between COVID-19 cases at nursing homes and measures of nursing home connectivity (to other homes).
Summary of Main Findings
Even after guidelines restricted social visitors at nursing homes beginning March 13, 2020, approximately 7% of mobile phones that were identified in a given nursing home during the study period were found in at least one other home. Nursing homes were also highly connected (mean number of connections: 15), though these estimates varied widely by state. In regression analysis, nursing home connectivity measures – including the number of other homes to which a nursing home was connected, the number of mobile phones identified in multiple nursing homes, and the number of shared contacts between a nursing home and other homes with high connectivity – were significantly associated with higher cumulative COVID-19 case counts. Higher cumulative COVID-19 cases were also associated with nursing homes in urban areas, more beds, and higher proportions of Black residents (>25%) and Medicaid recipients (>50%).
Investigators leveraged available geolocation data to identify networks of epidemiologically linked nursing homes vulnerable to COVID-19 transmission. Investigators performed sensitivity analyses to confirm that their findings were robust to COVID-19 prevalence and reporting differences across jurisdictions.
The study could not determine whether individuals whose phones appeared in multiple nursing homes were the actual source of SARS-CoV-2 transmission, since the outcome measure was COVID-19 cases aggregated to the nursing home level. Additionally, while geolocation services were useful in constructing nursing home network profiles, the data presented do not offer insights into the duration or frequency of individuals’ exposure to multiple facilities. Lastly, analyses were cross-sectional and did not account for temporal shifts in COVID-19 cases at nursing homes, which could have driven variability in mobility during the observation period that was unexamined in the study.
This study provides valuable evidence that long-term care facilities are highly connected via shared staff, highlighting potential transmission pathways that threaten vulnerable residents.
This review was posted on: 24 August 2020