Table 2.

Univariate Exact Poisson regression of secondary transmission by personal characteristics of index cases.

Variable	Case	No Case	Total	IRR	95% CI	p
Age				0.993	0.975–1.012	0.492
Age Group
18–29	19	31	50	1.180	0.591–2.353	0.638
30–39	23	23	46	2.054	1.056–3.990	0.034
40–49	29	126	155	1.380	0.729–2.613	0.321
50–62	14	61	75	1
Sex
Female	10	79	89	1
Male	75	162	237	1.351	1.060–1.725	0.015
Occupation
other professionals	2	39	41	1	-	-
Physician	26	89	115	5.777	1.371–24.342	0.017
nurse	36	82	118	3.512	0.845–14.586	0.084
auxiliary	15	29	44	3.529	0.807–15.433	0.094
orderlies	6	2	8	4.800	0.968–23.781	0.055