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Multifaceted strategies for the control of COVID-19 outbreaks in long-term care facilities in Ontario, Canada.

  • Vilches, Thomas N1
  • Nourbakhsh, Shokoofeh2
  • Zhang, Kevin3
  • Juden-Kelly, Lyndon2
  • Cipriano, Lauren E4
  • Langley, Joanne M5
  • Sah, Pratha6
  • Galvani, Alison P6
  • Moghadas, Seyed M2
  • 1 Institute of Mathematics, Statistics and Scientific Computing, University of Campinas, Campinas SP, Brazil. , (Brazil)
  • 2 Agent-Based Modelling Laboratory, York University, Toronto, Ontario, M3J 1P3 Canada. , (Canada)
  • 3 Faculty of Medicine, University of Toronto, Toronto, Ontario, M5S 1A8 Canada. , (Canada)
  • 4 Ivey Business School and Department of Epidemiology and Biostatistics, Schulich School of Medicine & Dentistry, Western University, London, Ontario N6G 0N1 Canada. , (Canada)
  • 5 Canadian Center for Vaccinology, Dalhousie University, IWK Health Centre and Nova Scotia Health Authority, Halifax, Nova Scotia, B3K 6R8 Canada. , (Canada)
  • 6 Center for Infectious Disease Modeling and Analysis (CIDMA), Yale School of Public Health, New Haven, Connecticut, USA.
Published Article
medRxiv : the preprint server for health sciences
Publication Date
Dec 07, 2020
DOI: 10.1101/2020.12.04.20244194
PMID: 33330884


COVID-19 has caused severe outbreaks in Canadian long-term care facilities (LTCFs). To evaluate the effect of mitigation measures in LTCFs including routine testing of staff and vaccination of staff and residents. Agent-based transmission model parameterized with disease-specific estimates, temporal sensitivity of nasopharyngeal (NP) and saliva testing, preliminary results of vaccine efficacy trials, and data from initial COVID-19 outbreaks in LTCFs in Ontario, Canada. Characteristics of staff and residents were included in the model with age-dependent risk of hospitalization and deaths, calibrated to the cumulative incidence of COVID-19 reported in these settings. Synthetic staff and resident populations. Routine NP and saliva testing of staff; vaccination of residents and staff. Daily incidence and attack rates in the LTCF using large-scale model simulations; estimates of hospitalizations and deaths and their 95% credible intervals. Weekly routine testing of staff with 2-day turnaround time reduced infections among residents by at least 20.3% (95% CrI: 18.7-21.8%), compared to baseline measures of mask-wearing, symptom screening, and staff cohorting alone. A similar reduction of hospitalizations and deaths was achieved in residents. Vaccination averted 2-4 times more infections in both staff and residents as compared to routine testing, and markedly reduced hospitalizations and deaths among residents by 81.4% (95% CrI: 80.6-82.2%), and 82.1% (95% CrI: 81.5-82.7%), respectively. Timelines of vaccine distribution and compliance rates with routine testing are key parameters affecting strategy outcomes. Routine testing of staff reduces silent transmission in LTCFs. Vaccination could have a substantial impact on mitigating disease burden among residents, but may not eliminate the need for other measures before population-level control of COVID-19 is achieved.

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