Table 2. Secondary household attack rates of SARS-CoV-2 B.1.1.7 variant infections among household contacts of primary cases from three childcare centre outbreaks, Hesse, January–February 2021.

Household situation	n/N	SAR in %	95% CI	RR	95% CI
All	34/92	37	28–47	NA	NA
Household CP is a child	9/28	32	18–51	0.82	0.44–1.52
Household CP is an adult	25/64	39	28–51	Ref
PC is a child (n = 22)	23/59	39	28–52	1.17	0.66–2.09
Household CP is a child	4/15	27	11–52	NA	NA
Household CP is an adult	19/44	43	30–58	NA	NA
PC is an adult (n = 16)	11/33	33	20–50	Ref
Household CP is a child	5/13	38	18–64	NA	NA
Household CP is an adult	6/20	30	15–52	NA	NA

CI: confidence interval; CP: contact person; n: number; N: total number; NA: not applicable; PC: primary case; Ref: reference; RR: relative risk; SAR: secondary attack rates; SARS-CoV-2: severe acute respiratory syndrome coronavirus 2.