August 1, 2025Open Access

Healthcare-Associated COVID-19 in Ontario, Canada: Relative Mortality and Contribution to Community Epidemic Growth

NWNatalie WilsonUniversity of North Carolina at Chapel Hill AGAlicia A. Grima3M (United States)ELEunyoung LeePublic Health Ontario

Key Points

Patients with moderate likelihood of healthcare-associated COVID-19 had 26% higher odds of death compared to those with lower likelihood.
No significant increase in mortality was observed for patients in the high-likelihood group of hospital-acquired infection.
Community cases did not predict hospital outbreaks, but hospital outbreaks significantly predicted community transmission growth.
Preventing hospital-acquired infections is vital to reduce mortality and control wider epidemic spread.

Abstract

Abstract Background The COVID-19 pandemic placed immense strain on Canada’s healthcare system and disproportionately affected individuals with poorer baseline health. Healthcare-associated infections (HAIs) increase risk for both patients and healthcare workers and are often more severe due to advanced age and comorbidities. While efforts have aimed to reduce in-hospital transmission, the individual- and community-level consequences of HAIs require further study. We aimed to assess whether healthcare-associated COVID-19 cases had higher odds of death compared to hospitalized community-acquired cases, and to evaluate the directionality of transmission between hospitals and the community. Methods We analyzed COVID-19 surveillance data from Ontario’s Case Contact and Management System and the COVaxON vaccine registry (March 17, 2020, to September 4, 2022). Latent class analysis was used to classify hospitalized cases by likelihood of healthcare-associated infection. Mortality odds by category were estimated using binomial logistic regression. Directionality between hospital outbreaks and community cases was assessed using a modified Granger causality approach. Findings Compared to patients with low likelihood of healthcare-associated infection, those moderately likely to have acquired COVID-19 in hospital had elevated odds of death (OR: 1.26, 95% CI: 1.14–1.40); no significant increase was seen in the high-likelihood group (OR: 1.05, 95% CI: 0.96–1.15). Community cases did not predict hospital outbreaks (p=0.5749), but hospital outbreaks predicted community case growth (p<0.0001). Interpretation Hospital-acquired COVID-19 is associated with excess mortality and may drive community transmission. Preventing in-hospital transmission is critical to protecting patients and controlling broader epidemic spread. Funding Supported by a Canadian Institutes for Health Research project grant, #518192.

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