Factors associated with transmission of COVID-19 in long-term care facility outbreaks

Abstract

Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has had a disproportionate impact on residents in long-term care facilities (LTCFs).

Aim: To identify risk factors associated with outbreak severity to inform current outbreak management and future pandemic preparedness planning efforts.

Methods: A retrospective cohort study design was used to evaluate the association between non-modifiable factors (facility building, organization level, and resident population characteristics), modifiable factors (measured through an assessment tool for infection prevention and control (IPC) and pandemic preparedness), and severity of COVID-19 outbreaks (attack rate) in LTCFs.

Findings: From March 1^st, 2020 to January 10^th, 2021, a total of 145 exposures to at least one confirmed case of COVID-19 in 82 LTCFs occurred. Risk factors associated with increased outbreak severity were older facility age, a resident (vs staff) index case, and poorer assessment tool performance. Specifically, for every item not met in the assessment tool, a 22% increase in the adjusted rate ratio was observed (1.2; 95% confidence interval: 1.1-1.4) after controlling for other risk factors.

Conclusion: Scores from an assessment tool, older building age, and the index case being a resident were associated with severity of COVID-19 outbreaks in our jurisdiction. The findings reinforce the importance of regularly assessing IPC measures and outbreak preparedness in preventing large outbreaks. Regular, systematic assessments incorporating IPC and outbreak preparedness measures may help mitigate impacts of future outbreaks and inform future pandemic preparedness planning.

Keywords: COVID-19; Long-term care; Risk factors.

Figure 1

Results of negative binomial regression models to examine risk factors associated with COVID-19 attack rates in long-term care facilities (LTCFs) in Fraser Health, March 1^st, 2020 to January 10^th, 2021 (N = 48 unique facilities). Standard errors are heteroskedasticity robust. ∗∗∗P < 0.001; ∗∗P < 0.01; ∗P < 0.05. ^aCommunity incidence calculated as incidence rate in the Local Health Area of the LTCF during the two weeks before symptom onset of index case. ^bAssessment score indicates the number of assessment items that were not met.

Fig S1