Table 1.

Baseline characteristics and the risk of seroconversion among the cohort of health care workers in the follow-up screening, May-June 2020, Cairo, Egypt (N = 2282).

	Total	Event/Person-days	Hazard (daily)	Unadjusted hazard ratio (95% CI)a	P-value
Overall	N = 2282 no. (%)	100/48746	0.21%
Age
18 to 29	960 (42.1)	15/19554	0.08%	Ref
30 to 39	587 (25.7)	33/12452	0.27%	3.42 (1.86–6.30)	<0.001
40 to 49	465 (20.4)	29/10232	0.28%	3.58 (1.91–6.70)	<0.001
≥ 50	270 (11.8)	23/6508	0.35%	4.19 (2.18–8.08)	<0.001
Gender
Male	792 (34.7)	22/16320	0.13%	Ref
Female	1490 (65.3)	78/32426	0.24%	1.63 (1.01–2.61)	0.044
Governorate of residence
Outside Cairo	525 (23.0)	18/10937	0.16%	Ref
Cairo	1757 (77.0)	82/37809	0.22%	1.24 (0.75–2.07)	0.407
Urban/rural residence
Urban	2004 (87.8)	89/42999	0.21%	Ref
Rural	278 (12.2)	11/5747	0.19%	0.96 (0.51–1.80)	0.895
Marital status
Not married	971 (42.6)	21/20226	0.10%	Ref
Married	1311 (57.4)	79/28520	0.28%	2.43 (1.50–3.94)	<0.001
Education
University or higher	1125 (49.3)	24/23857	0.10%	Ref
Secondary	928 (40.7)	55/19783	0.28%	2.56 (1.58–4.14)	<0.001
Primary or preparatory	153 (6.7)	13/3337	0.39%	4.42 (2.24–8.70)	<0.001
Less than primary	76 (3.3)	8/1769	0.45%	4.68 (2.09–10.47)	<0.001
Occupation
Physician	777 (34.0)	13/15968	0.08%	Ref
Nurse	946 (41.5)	54/20139	0.27%	3.01 (1.64–5.53)	<0.001
Non-clinical care	559 (24.5)	33/12639	0.26%	3.26 (1.70–6.22)	<0.001
Tobacco use
No	1983 (86.9)	91/42592	0.21%	Ref
Current	257 (11.3)	8/5358	0.15%	0.74 (0.36–1.53)	0.417
Past	42 (1.8)	1/796	0.13%	0.73 (0.10–5.26)	0.757
Self-reported pre-existing medical condition
No	1852 (81.2)	70/39167	0.18%	Ref
Yes	430 (18.8)	30/9579	0.31%	1.6 (1.04–2.45)	0.031

^aHazard ratio (95% CI) were calculated using Cox regression