Table 2.

Secondary attack rates in contacts with a serological or oral fluid outcome. Analysis excludes 55 households with a prior or co-primary case and 22 asymptomatic antibody positive PCR negative contacts whose timing of infection could not be established.

Factor	Level		n/N	% (95% CI)	P-value
All			75/248	33% (25–40)
Gender of contact		Female	34/120	31% (22–39)	0.516
		Male	41/128	34% (25–43)
Age of contact (years)		0to10	7/40	16% (4–28)	0.119
		11to18	11/40	33% (19–48)
		19to54	49/145	36% (28–45)
		>=55	8/23	32% (14–51)
Gender of index case		Female	42/139	33% (23–42)	0.998
		Male	33/109	32% (22–43)
Age of index case		0to10	14/61	25% (12–38)	0.346
		11to18	26/94	30% (19–41)
		19to54	26/73	36% (23–49)
		>=55	9/20	49% (24–73)
Index case self isolating		No	8/29	30% (10–51)	0.844
		Yes	66/217	33% (25–40)
Household size		2	15/28	54% (35–72)	0.009
		3	18/52	35% (20–50)	(trend)
		4	29/110	28% (18–38)
		5+	13/58	21% (8–35)
Minimum  Ct value in index case		35–40	12/38	31% (13–48)	0.44
		30–34	13/40	33% (17–50)	(trend)
		25–29	13/36	38% (20–56)
		20–24	13/43	33% (16–51)
		<20	6/14	45% (16–74)
Index case with loss taste/ smell		No	20/77	28% (16–40)	0.262
		Yes	53/153	37% (28–46)
1Index case with respiratory symptoms		No	2/38	6% (0–14)	0.003
		Yes	73/210	37% (29–45)
2Index case with gastro symptoms		No	29/103	30% (19–40)	0.526
		Yes	46/145	34% (25–44)
3Index case with systemic symptoms		No	2/22	10% (0–24)	0.048
		Yes	73/226	35% (27–42)

^{1. Cough}

^{shortness of breath}

^{sore throat}

^{runny nose}

^{2.  Nausea and diarrhoea}

^{3. Fever}

^headache

^fatigue

^{muscle/body pain}.