Table 4. Case-control study 3: Contacts between colleagues and airing of communal areas and risk of COVID-19 (all professions included).

Characteristics	Cases* (n = 109)	Controls* (n = 436)	OR [95% CI]	ORa [95% CI]
Age (years)
< 30	19 (17.4)	69 (15.8)	1 (ref)
30–39	32 (29.4)	128 (29.4)	1.02 [0.85–1.28]
40–49	31 (28.4)	128 (29.4)	1.03 [0.74–1.26]
≥ 50	27 (24.8)	111 (25.4)	1.11 [0.88–1.34]
Sex
Female	93 (85.3)	364 (83.5)	1 (ref)
Male	16 (14.7)	72 (16.5)	0.86 [0.70–1.04]
Contacts with colleagues
Eating at the workplace canteen
Never/rarely	63 (57.8)	252 (57.8)	1 (ref)
Regularly/always	46 (42.2)	184 (42.2)	1.00 [0.86–1.14]
Breaks with other colleagues
Never/rarely	44 (40.4)	171 (39.2)	1 (ref)
Regularly/always	65 (59.6)	265 (60.8)	0.95 [0.82–1.10]
Change of outfit in workplace changing rooms
Never/rarely	43 (39.4)	225 (51.6)	1 (ref)	1 (ref)
Regularly/always	66 (60.6)	211 (48.4)	1.92 [1.61–2.30]	1.93 [1.63–2.29]
Participation in professional meetings
Never/rarely	92 (84.4)	349 (80.0)	1 (ref)	1 (ref)
Regularly/always	17 (15.6)	87 (20.0)	0.73 [0.60–0.89]	0.72 [0.60–0.84]
Airing of communal areas
Never/rarely	28 (25.7)	114 (26.1)	1 (ref)
Regularly/always	81 (74.3)	322 (73.9)	1.03 [0.96–1.21]

OR: Odds ratio. ORa: Adjusted odds.

* Cases and controls were matched on workplace and occupation.