A Longitudinal, Clinical and Spatial Epidemiological Analysis of a Large COVID-19 Long-term Care Home Outbreak

Kain, Dylan; Stall, Nathan; Brown, Kevin; McCreight, Liz; Rea, Elizabeth; Kamal, Maya; Brenner, John; Verge, Melissa; Davies, Robert; Johnstone, Jennie

Objectives COVID-19 has had devastating effects on long-term care homes across much of the world, and especially within Canada, with over 50% of the mortality from COVID-19 in 2020 in these homes. Understanding the way in which the virus spreads within these homes is critical to preventing further outbreaks. Design Retrospective chart review. Settings and Participants Long-term care home residents and staff in Ontario, Canada. Methods We conducted a longitudinal study of a large long-term care home COVID-19 outbreak in Ontario, Canada using electronic medical records, public health records, staff assignments and resident room locations to spatially map the outbreak through the facility. Results By analyzing the outbreak longitudinally we were able to draw three important conclusions: 1) 84.5% had typical COVID-19 symptoms and only 15.5% of residents had asymptomatic infection, 2) there was a high attack rate of 85.8%, which appeared to be explained by a high degree of interconnectedness within the home exacerbated by staffing shortages, and 3) clustering of infections within multi-bedded rooms was common. Conclusion and Implications Low rates of asymptomatic infection suggest symptom-based screening in residents remains very important for detecting outbreaks, a high degree of interconnectedness explains the high attack rate and there is a need for improved guidance for homes with multi-bedded rooms on optimizing resident room movement to mitigate spread of COVID-19 in long-term care homes.