Table 7. Univariate and multivariate analysis of pandemic (H1N1) 2009 SAR infection for acute respiratory infection, by gender, age group and prophylaxis, United Kingdom, 2009*.

Variable	No. contacts†	No. secondary case-patients	Univariate analysis			Multivariate analysis
			SAR, % (95% CI)	p value‡		OR (95% CI)	p value
Sex, n = 704
M	339	56	16.5 (12.9–20.9)			1.0, baseline
F	365	64	17.5 (12.5–24)	0.72		1.9 (1.0–3.5)	0.04
Age, y
<16	194	49	25.3 (15.4–38.6)			7.0 (3.0–21.0)
16–49	359	56	15.6 (9.2–25.2)			3.6 (1.5–8.8)
>50	166	15	9.0 (5.5–14.4)	<0.001		1.0, baseline	0.001
Prophylaxis, n = 549
No	106	80	75.5 (66.4–82.7)			1, baseline
Yes	443	34	7.7 (4.5–12.7)	<0.001		0.02 (0.01–0.03)	<0.001
Primary case-patient treatment
>48 h	435	79	18.2 (14.8–22.1)			1, baseline
<48 h	284	41	14.4 (10.1–20.3)	0.019		1.7 (0.9–3.1)	0.11
Total	719	120	16.7 (14.1–19.6)

*n = 719 except as indicated. Hosmer-Lemeshow goodness-of-fit test for multivariate model, p = 0.392. SAR, secondary attack rate; CI, confidence interval; OR, odds ratio.
†Excludes coprimary case-patients.
‡Indicates overall p-value for differences by group.