Epidemiology, clinical characteristics, household transmission, and lethality of severe acute respiratory syndrome coronavirus-2 infection among healthcare workers in Ontario, Canada

Abstract

Introduction Protecting healthcare workers (HCWs) from Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) is a priority to maintain a safe and functioning healthcare system. Our objective was to describe and compare the epidemiology, clinical characteristics, and lethality of SARS-CoV-2 infections among HCWs compared to non-HCWs. Methods Using reportable disease data at Public Health Ontario, we conducted a population-based cross-sectional study comparing demographic, exposure, and clinical variables between HCWs and non-HCWs with SARS-CoV-2 infections as of 30 September 2020. We calculated rates of infections over time and determined the frequency of within household transmissions using natural language processing based on residential address. We evaluated the risk of death using a multivariable logistic regression model adjusting for age, sex, comorbidities, symptoms, and long-term care home exposure. Results There were 7,050 (12.5%) HCW SARS-CoV-2 infections in Ontario, Canada, of whom 24.9% were nurses, 2.3% were physicians, and the remaining 72.8% other specialties, including personal support workers. Overall HCWs had an infection rate of 1,276 per 100,000 compared to non-HCWs of 346 per 100,000 (3.7 times higher). This difference decreased from a 7 times higher rate in April to no difference in September 2020. Twenty-six percent of HCWs had a household member with SARS-CoV-2 infection; 6.8% were probable acquisitions, 12.3% secondary transmissions, and 6.9% unknown direction of transmission. Death among HCWs was 0.2% compared to 6.1% of non-HCWs. The risk of death in HCWs remained significantly lower than non-HCWs after adjustment (adjusted odds ratio 0.09; 95%CI 0.05–0.17). Conclusion HCWs represent a disproportionate number of diagnosed SARS-CoV-2 infections in Ontario, however this discrepancy is at least partially explained by limitations in testing earlier in the pandemic for non-HCWs. We observed a low risk of death in HCWs which could not be completely explained by other factors.

Characterization and evolution of infection control practices among severe acute respiratory coronavirus virus 2 (SARS-CoV-2)–infected healthcare workers in acute-care hospitals and long-term care facilities in Québec, Canada, Spring 2020

“…19 Ontario reported a rate 5.5 times higher for HCWs compared with non-HCWs. 5 In Scotland, hospital HCWs had a 3.4 times higher prevalence of SARS-CoV-2 antibodies than age-and sex-matched controls of general population (14.5% vs 4.8%). 20 In Wuhan, the attack rates among HCWs were 5.4 times higher than among non-HCWs.…”

“…This rate is higher than the 17% pooled estimation from a recent meta-analysis of published studies in which secondary attack rates in households varied between 4% and 36%. 5 Patient-facing staff, mostly nurses and physicians, have been identified as occupations at highest risk, but most of these studies were hospital based. 12,13,[22][23][24] In our study, 35% of all infected HCWs were healthcare support workers (51% in LTCFs), 23% were nurses, 12% were nurse assistants, and 45% worked in LTCFs.…”

“…College of Physicians of Québec, data updated in 2019 4. Québec Order of Nurses, data updated 2019 5. Québec Order of Nurse Assistants, data updated 2019.…”

Temporal Trends in COVID-19 Incidence in Two Healthcare Worker Cohorts

“… 8 The Toronto-based analysis cited previously also showed the HCW rates paralleled and even preceded wider population trends. 1 …”

COVID-19 Workplace Outbreaks by Industry Sector and Their Associated Household Transmission, Ontario, Canada, January to June, 2020

“… 5 Previous studies have shown the impacts from workplace outbreaks beyond the affected cases to their surrounding community adding to the overall burden of illness from household and community transmission. 3 , 9 Identifying vulnerable industry sectors and their related community transmission is necessary to target public health interventions to prevent outbreaks and subsequent community spread. Our objectives were to: (1) describe workplace outbreaks in Ontario over the first 6 months of 2020 (the first wave of the SARS-CoV-2 pandemic and initial stages of re-opening); (2) describe cases associated with these workplace outbreaks; and (3) estimate the additional burden of illness due to associated household transmission.…”