Table 2. Pandemic (H1N1) 2009 attack rates among 223 household contacts of 87 index patients, by patient characteristics and symptoms, Taiwan, August–November 2009*.

Characteristic	Attack rate, %	OR (95% CI)†	p value†
Sex			0.21
M, n = 101	23	Reference
F, n = 122	30	1.48 (0.81–2.70)
Age, y			<0.0001
>18, n = 166	15	Reference
<18, n = 57	61	9.09 (4.55–17.86)
Signs and symptoms
Fever			<0.0001
No, n = 163	12	Reference
Yes, n = 60	68	16.13 (7.87–33.33)
Cough			<0.0001
No, n = 158	13	Reference
Yes, n = 65	60	10.42 (5.29–20.83)
Rhinorrhea			<0.0001
No, n = 176	19	Reference
Yes, n = 47	55	5.18 (2.60–10.31)
Sore throat			0.0002
No, n = 176	21	Reference
Yes, n = 47	49	3.60 (1.83–7.09)
Vomiting			0.06
No, n = 214	26	Reference
Yes, n = 9	56	3.60 (0.93–13.90)
Diarrhea			0.23
No, n = 214	26	Reference
Yes, n = 9	44	2.30 (0.60–8.85)
Malaise			0.002
No, n = 200	24	Reference
Yes, n = 23	57	4.20 (1.73–10.20)
Myalgia			0.02
No, n = 192	24	Reference
Yes, n = 31	45	2.61 (1.20–5.71)

*OR, odds ratio; CI, confidence interval.
†Univariate logistic regression model was used for unadjusted OR (95% CI) and unadjusted p values. If features were significantly different with p<0.05 in univariate logistic regression model, they were further analyzed with multiple logistic regression model for adjusted OR (95% CI) and adjusted p values.