Table 2. Case-control study 1: Exposures associated with risk of COVID-19 among HCWs caring for COVID-19 patients.

Characteristics	Cases* (n = 70)	Controls* (n = 280)	OR [95% CI]	ORa [95% CI]
Age (years)
< 30	14 (20.0)	55 (19.6)	1 (ref)	1 (ref)
30–39	22 (31.4)	84 (28.9)	1.06 [0.87–1.30]	1.16 [0.93–1.44]
40–49	17 (24.3)	85 (30.4)	0.91 [0.73–1.10]	0.97 [0.76–1.20]
≥ 50	17 (24.3)	59 (21.1)	1.34 [1.05–1.67]	1.26 [0.97–1.61]
Sex
Female	61 (87.1)	239 (85.4)	1 (ref)
Male	9 (12.9)	41 (14.6)	0.85 [0.66–1.08]
Preventative measures (PPE wearing and other)
Handrubbing with alcohol based handrub before and after patient care
Never/rarely	0 (0)	8 (2.9)	-
Regularly/always	70 (100)	272 (97.1)	-
Type of mask used
Mainly surgical masks	22 (31.4)	55 (19.6)	1 (ref)	1 (ref)
Surgical masks + respirators during aerosol-generating procedures	35 (50.0)	148 (52.9)	0.54 [0.43–0.65]	0.56 [0.43–0.70]
Mainly respirators	13 (18.6)	77 (27.5)	0.38 [0.29–0.46]	0.39 [0.29–0.51]
Face shield or protective goggles
Never/rarely	30 (42.9)	106 (37.9)	1 (ref)	1 (ref)
Regularly/always	40 (57.1)	74 (62.1)	0.82 [0.70–0.94]	1.27 [0.99–1.55]
Disposable gown and plastic apron when needed
Never/rarely	13 (18.6)	37 (13.2)	1 (ref)	1 (ref)
Regularly/always	57 (81.4)	243 (86.8)	0.64 [0.50–0.79]	0.96 [0.70–1.26]
Gloves, for all types of patient care
Never/rarely	12 (17.1)	48 (17.1)	1 (ref)
Regularly/always	58 (82.9)	232 (82.9)	0.99 [0.78–1.22]
Protective hair cap
Never/rarely	33 (47.1)	106 (37.9)	1 (ref)	1 (ref)
Regularly/always	37 (52.9)	174 (62.1)	0.67 [0.58–0.78]	0.78 [0.63–0.98]
Protective overshoes
Never/rarely	56 (80.0)	218 (77.9)	1 (ref)
Regularly/always	14 (20.0)	62 (22.1)	0.88 [0.74–1.05]
Regular airing of patients/residents’ rooms
Never/rarely	24 (34.3)	91 (32.5)	1 (ref)
Regularly/always	46 (65.7)	189 (67.5)	0.91 [0.76–1.07]

OR: Odds ratio. ORa: Adjusted odds ratio.

* Cases and controls were matched on workplace and occupation.