SARS-CoV-2 Exposures of Healthcare Workers from Primary Care, Long-Term Care Facilities and Hospitals: A Nationwide Matched Case-Control Study

Abstract

Objectives. Healthcare workers (HCWs) are at higher risk of contracting coronavirus disease 19 (COVID 19) than the general population. This study assessed the roles of various exposures and personal protective equipment (PPE) use on that risk for HCWs working in primary care, long term care facilities (LTCFs) or hospitals. Methods. We conducted a matched case-control (1:1) study (10 April; 9 July 2021). Cases (HCWs with confirmed COVID-19) and controls (HCWs without any COVID 19 positive test or symptoms) recruited by email were invited to complete an online questionnaire on their exposures and PPE use. Questions covered the 10 days preceding symptom onset for cases (or testing if asymptomatic) or inclusion for controls. Results. A total of 4152 matched cases and controls were included. The multivariable conditional logistic regression analysis retained exposure to an infected person outside work (adjusted odds ratio, 19.9 [95% confidence intervaI, 12.4, 31.9]), an infected colleague (2.26 [1.53, 3.33]) or COVID-19 patients (2.37 [1.66, 3.40]), as independent predictors of COVID-19 in HCWs, while partial or complete immunization was protective. Eye protection (0.57 [0.37, 0.87]) and wearing a gown (0.58 [0.34, 0.97]) during COVID-19 patient care were protective, while wearing an apron slightly increased the risk of infection (1.47 [1.00, 2.18]). N95-respirator protection was comparable to that of surgical masks. Results were consistent across healthcare-facility categories. Conclusions. HCWs were more likely to get COVID-19 in their personal sphere than during occupational activities. Our results suggest that eye protection for HCWs during patient care should be actively promoted.

Sars-Cov-2 exposures of healthcare workers and acquisition of COVID-19

“…Similar to the findings of Belan et al 7 , a prospective cohort study at nine healthcare institutions from Switzerland found household exposure to be the strongest risk factor (adjusted hazard ratio 10.1; 95% CI 7·5−13·5) for both HCW SARS-CoV-2 swab positivity and seroconversion in a multivariate regression analysis. 11 This study also found no significant difference between the use of a filtering facepiece class 2 (FFP2) respirator versus the use of a surgical mask 11 which is consistent with the updated systematic review of observational studies for risk factors for COVID-19 among HCWs mentioned above, albeit recognizing the limitations of observational studies.…”

“…The matched case-control study reported by Belan et al 7 which assessed HCW COVID-19 exposures and PPE use was unique since it included HCWs working across the spectrum of healthcare delivery including acute care, long term care facilities (LTCFs) and primary care. The strengths included its large size, nationwide scope, age, sex, and regional domicile matching, timing for inclusion, and prompt contact to reduce recall bias.…”

“…The study by Belan 7 has limitations which have been outlined by the authors and there remain concerns over recall bias, self reported compliance with PPE, lack of auditing, and no mention of FFP2 fit checking although all HCWs in France should have been fit tested. Assessment of collinearity between the individual components of PPE was not mentioned and other intrinsic biases associated with a case-control design still exist (lincluding lack of blinding of analysts to case or control status, contamination bias, ascertainment bias, detection bias and non-responder bias).…”

“…A smaller study done in the UK at the J o u r n a l P r e -p r o o f same time at a London teaching hospital observed that the rates of positivity amongst frontline HCWs paralleled the frequency of community-associated cases. 6 The matched case-control study reported by Belan et al 7 which assessed HCW COVID-19 exposures and PPE use was unique since it included HCWs working across the spectrum of healthcare delivery including acute care, long term care facilities (LTCFs) and primary care. The strengths included its large size, nationwide scope, age, sex, and regional domicile matching, timing for inclusion, and prompt contact to reduce recall bias.…”

Risk and protective factors for severe acute respiratory coronavirus virus 2 (SARS-CoV-2) infection among healthcare workers: A test-negative case–control study in Québec, Canada

“…Similar to the literature, in our study the highest risk of transmission among HCWs was associated with COVID-19 contacts in the household (13-fold), where infection prevention measures may not be routinely followed and prolonged contacts at short distances occur frequently. 5,13,14,22,27,31 Household exposure was only reported by 9% of high-risk caregiver cases during the study period. This low prevalence of nonoccupational contacts might be to due underreporting associated with undetected asymptomatic infections or to the lack of benefit of occupational insurance coverage for HCWs reporting household acquisition.…”