Table 2.

Model-based estimates of secondary attack rates among household and non-household contacts, and local R with and without quarantine

		Mean incubation period of 5 days		Mean incubation period of 7 days
		13-day infectious period	22-day infectious period	13-day infectious period	22-day infectious period
Close relatives
Secondary attack rate, % (95% CI)
	Household	12·4% (9·8–15·4)	15·5% (11·7–20·2)	11·4% (9·0–14·2)	13·1% (9·9–17·1)
	Non-household	7·9% (5·3–11·8)	10·4% (6·7–15·8)	7·5% (5·0–11·2)	8·9% (5·7–13·6)
Local R (95% CI)
	With quarantine	0·50 (0·41–0·62)	0·51 (0·39–0·66)	0·51 (0·41–0·63)	0·51 (0·39–0·67)
	No quarantine	0·60 (0·49–0·74)	0·76 (0·59–1·00)	0·56 (0·45–0·69)	0·65 (0·49–0·85)
Residential address
Secondary attack rate, % (95% CI)
	Household	17·1% (13·3–21·8)	21·2% (15·8–27·8)	16·1% (12·5–20·4)	18·3% (13·6–24·1)
	Non-household	7·3% (5·4–9·9)	9·3% (6·5–13·1)	6·8% (5·0–9·2)	7·8% (5·5–11·0)
Local R (95% CI)
	With quarantine	0·50 (0·40–0·61)	0·50 (0·38–0·65)	0·50 (0·41–0·62)	0·51 (0·39–0·66)
	No quarantine	0·59 (0·48–0·72)	0·74 (0·57–0·96)	0·55 (0·45–0·67)	0·63 (0·48–0·82)

Estimates were reported using two different definitions of household contact (close relatives or individuals sharing the same residential address) and for selected settings of the natural history of disease. This model was not adjusted for age group, epidemic phase, or household size. R=reproductive number.