Table 7.

Risk factors of COVID-19 infection in healthcare worker populations.

Reference	Risk factor category	Data
Felice et al. (2020)	Personal protective equipment (PPE)	PPEs were more readily available in high-risk specialty sectors OR 1.96 (95% CI 0.98–3.94) vs. less likely for HCW with recent onset of symptoms OR 0.48 (95% CI 0.28–0.83)
Nguyen et al. (2020a, Nguyen et al., 2020	PPE	Compared with HCW with adequate PPE supply:
		•Re-use of PPE had an increased risk of a positive COVID-19 test (adjusted HR 1.46, 95% CI 1.21–1.76) vs. those with inadequate PPE (adjusted HR 1.31, 95% CI 1.10–1.56)
		•Inadequate PPE and caring for patients with documented COVID-19 (adjusted HR 5.91, 95% CI 4.53–7.71) vs. with adequate PPE not caring for patients with suspected or documented COVID-19
		•Reusing PPE and exposed to patients with documented COVID-19: (adjusted HR 5.06, 95% CI 3.90–6.57)
		•Adequate PPE and caring for patients with suspected COVID-19 (adjusted HR 2.39, 95% CI 1.90–3.00) and for those caring for patients with documented COVID-19 (4.83, 3.99–5.85) compared with healthcare workers who did not care for either group
Ran et al. (2020)	PPE	Compared to HCW without infection:
		•Unqualified handwashing: RR 2.64 (95% CI 1.04−6.71, p < 0.05)
		•Suboptimal hand hygiene before contact with patients: RR 3.10 (95% CI 1.43–6.73, p < 0.01)
		•Suboptimal hand hygiene after contact with patients:: RR 2.43 (95% CI 1.34–4.39, p < 0.01)
		•Improper PPE: RR 2.82 (95% CI 1.11–7.18)
Chen et al. (2020)	PPE	Face mask use reduced risk of infection OR 0.127 (95% CI 0.017–0.968)
Guo et al. (2020)	PPE	•Participating in infection control training was associated with a decreased risk of infection OR 0.12 (95% CI 0.03–0.57)
		•Non-compliance to wearing N95 masks increased risk OR 5.20 (95% CI 1.09–25.00)
		•Wearing masks or respirators all the time decreased risk OR 0.15 (95% CI 0.04–0.55)
		•Suspect patient not wearing mask OR 6.05 (95% CI 1.70–21.51)
		•Adherence to recommended hand-hygiene practice associated with a decreased risk of infection OR = 0.15 (95% CI 0.04–0.55)
Felice et al. (2020)	Exposure	Those reporting typical symptoms during the last two weeks were more likely, but not statistically significant, to come from high-prevalence regions OR 1.48 (95% CI 0.93–2.37)
Korth et al. (2020)	Exposure	Seroprevalence: Higher in the intermediate-risk (with daily non-COVID-19 patient contact) vs. high-risk group (daily contact to COVID-19 patients on the designated wards and on the intensive care units) OR 0.22 (confidence interval (95% CI 0.04–1.35)
Nguyen et al. (2020a)	Workplace setting	Compared with risk for the general community, risk for front-line healthcare workers was increased in all healthcare settings, but was highest for those working in inpatient settings (adjusted HR 24.30, 95% CI 21.83–27.06) and nursing homes (16.24, 13.39–19.70)
Ran et al. (2020)	Workplace setting	High-risk department (with interventional medical or surgical procedures that generate respiratory aerosols, including the respiratory department, infection department, ICU and the surgical department) vs. general department group (crude RR 2.13, 95% CI 1.45–3.95, p < 0.05).
Garzaro et al. (2020)	Workplace setting	Sharing work environment was associated with increased risk OR 2.63 (95% CI 1.34–5.32)
Chen et al. (2020)	Profession	Risk of infection highest in physicians exposed to positive COVID-19 patients OR 346.83 (95% CI 8.924–13479.434) compared with nurses OR 19.523 (95% CI 0.667–571.463) or general service employees OR 13.294 (95% CI 0.265–666.605)
Garzaro et al. (2020)	Profession	•Physicians at increased risk OR 2.03 (95% CI 1.18–3.49)
		•HCWs working in the maternity hospital had more risk of infection OR 2.94 (95% CI 1.72–4.95)
Ran et al. (2020)	Contacts	•Diagnosed family member: RR 2.76 (95% CI 2.02–3.77, p < 0.01)
		•Diagnosed patient: RR 0.36 (95% CI 0.22–0.59, p < 0.01)
		Suspected patient: RR 0.49 (95% CI 0.27–0.89, p < 0.05)
Felice et al. (2020)	Testing	•Testing of symptomatic HCW COVID-19 adjusted OR 3.61 (95% CI 2.15–6.06) vs. asymptomatic, less than a half (45%) of symptomatic HCW was actually screened for COVID-19