Table 1.

Impact of parameters on seropositivity rate

Parameter	Categories	N	Positive (%)	OR (95% CI)a	OR (95% CI)b
Sex	Female	4174	323 (7.7)	1.00
	Male	1059	74 (7.0)	0.86 (0.66–1.12)
Age		5233	397 (7.6)	0.98 (0.97–0.99)	0.99 (0.98–0.99)
Profession	Nursing staff	2660	265 (10.0)	1.00	1.00
	Medical staff	596	38 (6.4)	0.64 (0.44–0.91)	0.65 (0.43–0.94)
	Paramedical staff	671	40 (6.0)	0.60 (0.42–0.84)	0.74 (0.51–0.94)
	Administrative staff	654	19 (2.9)	0.23 (0.14–0.36)	0.40 (0.24–0.66)
	Cleaning and technical services staff	652	35 (5.4)	0.46 (0.31–0.65)	0.63 (0.43–0.93)
Working on a COVID-19 ward	No	3289	172 (5.2)	1.00	1.00
	Yes	1944	225 (11.6)	2.47 (1.98–3.08)	1.73 (1.36–2.20)
Close colleague at work had confirmed COVID-19	No	2940	123 (4.2)	1.00	1.00
	Yes	2293	274 (12.0)	2.63 (2.10–3.31)	1.84 (1.43–2.36)
Contact with confirmed/suspected COVID-19 cases in private setting	No	4783	327 (6.8)	1.00	1.00
	Yes	450	70 (15.6)	2.62 (1.96–3.47)	2.56 (1.91–3.42)
Contact with confirmed/suspected COVID-19 cases at work with adequate protection	No	3375	230 (6.8)	1.00
	Yes	1858	167 (9.0)	1.22 (0.99–1.51)
Accidental unprotected contact with confirmed/suspected COVID-19 cases at work accidental	No	1657	61 (3.7)	1.00
	Yes	3576	336 (9.4)	2.58 (1.95–3.45)
Contact with confirmed/suspected COVID-19 cases at work: protected and/or accidental and unprotected	No contact	1425	42 (2.9)		1.00
	Only protected contact	1950	188 (9.6)		1.74 (1.19–2.54)
	Only accidental and unprotected contact	232	19 (8.2)		1.44 (0.80–2.59)
	Protected and accidental and unprotected contact	1626	148 (9.1)		1.17 (0.78–1.75)

N, number of observations; OR, odds ratio; CI, confidence interval.

^aUnivariate model using hospital sites as random effect.

^bMultivariate model using hospital sites as random effect and with interaction term for contact at work ‘protected’ and ‘accidental and unprotected’.