Healthcare Worker COVID-19 Cases in Ontario, Canada: A Cross-sectional Study

Schwartz, K. L.; Achonu, C.; Buchan, S. A.; Brown, K. A.; Lee, B.; Whelan, M.; Wu, J. H.; Garber, G.

Background: Our objectives were to describe and compare healthcare worker (HCW) and non-HCW COVID-19 cases in Ontario, as well as the frequency of COVID-19 among HCWs household members. Methods: Using reportable disease data at Public Health Ontario which captures COVID-19 cases in Ontario, we conducted a cross-sectional study comparing demographic, exposure, and clinical variables between HCWs and non-HCWs with COVID-19 as of 14 May 2020. We calculated rates of infections over time and determined the frequency of within household transmissions using natural language processing. Results: There were 4,230 (17.5%) HCW COVID-19 cases in Ontario, of whom 20.2% were nurses, 2.3% were physicians, and the remaining 77.4% other specialties. HCWs were more likely to be between 30-60 years of age and female. HCWs were more likely to present asymptomatically (8.1% versus 7.0%, p=0.010) or with atypical symptoms (17.8% versus 10.5%, p<0.001). The mortality among HCWs was 0.2% compared to 10.5% of non-HCWs. HCWs commonly had exposures to a confirmed case or outbreak (74.1%), however only 3.1% were confirmed to be nosocomial. The rate of new infections was 5.5 times higher in HCWs than non-HCWs, but mirrored the epidemic curve. We identified 391 (9.8%) probable secondary household transmissions. Interpretation: HCWs represent a disproportionate number of COVID-19 cases in Ontario but with low confirmed numbers of nosocomial transmission. The data support substantial testing bias and under-ascertainment of general population cases. Protecting HCWs through appropriate personal protective equipment and physician distancing from colleagues is paramount.