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

Vilches, Thomas N.; Nourbakhsh, Shokoofeh; Zhang, Kevin; Juden-Kelly, Lyndon; Cipriano, Lauren E.; Langley, Joanne M.; Sah, Pratha; Galvani, Alison P.; Moghadas, Seyed M.

BACKGROUND: COVID-19 has caused severe outbreaks in Canadian long-term care facilities (LTCFs). OBJECTIVE: To evaluate the effect of mitigation measures in LTCFs including routine testing of staff and vaccination of staff and residents. DESIGN: 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. SETTING: 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. PARTICIPANTS: Synthetic staff and resident populations. INTERVENTIONS: Routine NP and saliva testing of staff; vaccination of residents and staff. MEASUREMENTS: Daily incidence and attack rates in the LTCF using large-scale model simulations; estimates of hospitalizations and deaths and their 95% credible intervals. RESULTS: 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. LIMITATIONS: Timelines of vaccine distribution and compliance rates with routine testing are key parameters affecting strategy outcomes. CONCLUSION: 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.