We described the evolution of SARS-CoV-2 source of infection in a cohort of healthcare workers (HCWs) of Quebec, Canada, during the first three pandemic waves. We also estimated their household secondary attack rate (SAR) and its risk factors.

Cross-sectional surveys.

HCWs with a SARS-CoV-2 infection confirmed by polymerasa chain reaction and diagnosed between March 2020 and May 2021.

We collected demographic, clinical, vaccination, and employment information, self-reported perceived source of infection, and transmission to household members during the first three pandemic waves. SAR was calculated for households with ≥2 members where the HCW was the index case. A Poisson regression model estimated the association between risk factors and SAR.

Among the 11,670 HCWs completing the survey, 91%, perceived their workplace as the source of infection during the first wave (March–July 2020), 71% during the second wave (July 2020–March 2021), and 40% during the third wave (March–May 2021). Conversely, HCWs reported an increasing proportion of household-acquired infections with each wave from 4% to 14% and 33%, respectively. The overall household SAR of 7,990 HCWs living with ≥1 person was 30% (95%CI: 29–30). SAR increased with the presence of symptoms, older age, and during Alpha-variant predominant period.

HCWs and their household members were largely affected during the first pandemic waves of COVID-19, but the relative importance of occupational exposure changed overtime. Pandemic preparedness in healthcare settings is essential to protect HCWs from emerging biological hazard exposures.

In this study, we aimed to (1) estimate the severe acute respiratory coronavirus 2 (SARS-CoV-2) infection rate and the secondary attack rate among healthcare workers (HCWs) in Québec, the most affected province of Canada during the first wave; (2) describe the evolution of work-related exposures and infection prevention and control (IPC) practices in infected HCWs; and (3) compare the exposures and practices between acute-care hospitals (ACHs) and long-term care facilities (LTCFs).

Survey of cases.

The study included Québec HCWs from private and public institutions with laboratory-confirmed coronavirus disease 2019 (COVID-19) diagnosed between March 1 and June 14, 2020. HCWs aged ≥18 years who worked during the exposure period and survived their illness were eligible for the survey.

After obtaining consent, 4,542 HCWs completed a standardized questionnaire. COVID-19 rates and proportions of exposures and practices were estimated and compared between ACHs and LTCFs.

HCWs represented 13,726 (25%) of 54,005 reported COVID-19 cases in Québec and had an 11-times greater rate of COVID-19 than non-HCWs. Their secondary household attack rate was 30%. Most affected occupations were healthcare support workers, nurses and nurse assistants working in LTCFs (45%) and ACHs (30%). Compared to ACHs, HCWs in LTCFs had less training, higher staff mobility between working sites, similar PPE use, and better self-reported compliance with at-work physical distancing. Suboptimal IPC practices declined over time but were still present at the end of the first wave.

Québec HCWs and their families were severely affected during the first wave of COVID-19. Insufficient pandemic preparedness and suboptimal IPC practices likely contributed to high transmission in both LTCFs and ACHs.