Connectivity between long-term care homes and subsequent SARS-CoV-2 outbreaks

Objectives To describe the relationship between individual workers employed at more than one LTCH (inter-LTCH connectivity) across long-term care homes (LTCH) and SARS-CoV-2 outbreaks. Design A retrospective cohort study using long-term care home surveillance and mobile geolocation data. Setting Using data observed between February 26th, 2020, and August 31st, 2020, from Ontario, the province where close to one-third of the Canada’s SARS-CoV-2 cases among long-term care homes residents were reported. Participants We included all 179 LTCH in the Greater Toronto Area (population 6.7 million, where close to 50% of Ontario population resides). Exposures The main exposure of interest was the inter-LTCH connectivity, generated from geographic position system location data procured across apps on different platforms. Main outcomes and measures Three outcomes were examined: 1) at least one SARS-CoV-2 diagnosis among residents, 2) cumulative cases among residents in each facility, and 3) time to first outbreak.

The median degree of connectivity for LTCH that experienced an outbreak (59%; 106/179) was 1.2 times the degree of those without an outbreak (6 compared to 5). LTCH with higher inter-LTCH connectivity also had larger numbers of residents and beds, and were more likely to have for-profit ownership. After adjusting for facility-level and neighbourhood-level factors, every additional connection to another LTCH increased the odds of an outbreak in the respective LTCH by 8% (adjusted odds ratio=1.08, 90% credible interval [CrI]: 1.02-1.09). Inter-LTCH connectivity was also associated with higher risk of earlier occurrence of a first SARS-CoV-2 case (adjusted hazard ratio=1.05, 90%CrI: 1.02-1.09), but not with outbreak size.

and Relevance Staff cohorting was associated with reduced importation risk of SARS-CoV-2 cases into LTCH. However, findings suggest that once importation has occurred, other facility-level factors including facility infrastructure and staff benefits are more important in shaping outbreak size. Implementing these structural strategies to meet the LTCH workers and residents’ needs are pivotal to prevent and manage future respiratory virus outbreaks. Question Were movement of long-term care homes (LTCH) workers between facilities (staff connectivity) associated with the risk, size, and timing of SARS-CoV-2 outbreaks in these facilities during the first wave of the COVID-19 pandemic. Finding After adjusting for facility-level and neighbourhood-level factors, a higher degree of staff connectivity between LTCH was associated with a greater risk of outbreaks (2.2-fold the risk of a LTCH connected with 10 more other LTCHs) and a higher risk of experiencing an earlier outbreak (1.7-fold the hazard with 10 more staff connections with other LTCH). However, we did not observe an association between connectivity and the size of outbreaks. Meaning “One-site” strategy to cohort staff by facility and minimizing movement may reduce risk of pathogen importation. However, structural strategies (e.g. improve facility design and infrastructure) to reduce nosocomial transmission within these facilities remain pivotal to prevent and manage future respiratory virus outbreaks. Competing Interest Statement The authors have declared no competing interest. Funding Statement This study was funded by the COVID-19 Immunity Task Force via the Public Health Agency of Canada (#2021-HQ-000143). Sharon E Straus′s research program is supported by a Canada Research Chair (Tier 1) in Knowledge Translation and Quality of Care. Sharmistha Mishra′s research program is supported by a Canada Research Chair (Tier 2) in Mathematical Modeling and Program Science. Mathieu Maheu-Giroux′s research program is supported by a Canada Research Chair (Tier 2) in Population Health Modeling. Yiqing Xia′s work is supported by the CIHR doctoral award. Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Ethics approval was obtained from the Unity Health Toronto Research Ethics Board (#23-198). I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes Data Availability All data except for long-term care home SARS-CoV-2 cases and occupation are publicly available information.