Table 5. Summary of stepwise multivariate logistic regression model predicting “probable secondary infection” within the household level^a.

Risk factor	Coefficient	SE	Odds ratio (95% CI)	p value
Type of Index Person (IP)
Healthcare worker			1.00
Amoy Gardens Block E residents	3.074	0.487	21.62 (8.33 to 56.10)	<0.001
Amoy Gardens other Block residents	1.901	0.425	6.69 (2.91 to 15.39)	<0.001
Other community member	1.705	0.354	5.50 (2.75 to 11.01)	<0.001
Date of IP’s fever onset
Before March 25			1.00
On or after March 25	–0.696	0.235	0.50 (0.32 to 0.79)	<0.001
Duration IP stayed home between fever onset and hospitalization (d)
<2			1.00
3–5	0.283	0.258	1.33 (0.80 to 2.20)	0.274
>6	1.045	0.265	2.84 (1.69 to 4.78)	<0.001
IP visited by any household member when hospitalized?
No			1.00
Yes	0.483	0.242	1.62 (1.01 to 2.60)	0.046

^aAge was not significant in the multivariable analysis.