Table 2.

Characteristics of the daycare groups with at least one acute laboratory-confirmed SARS-CoV-2 case, COALA study, Germany, 10/2020–06/2021

Daycare group	Month of outbreak	Type of primary case	Number of close contacts	Number of participating close contactsa	Number of secondary transmissions	Secondary attack rate	Number of close contacts with existing antibodies at day 0	Virus variant
1	10/20	Child	18	13	0	0.0	0	Wildtype/non-VOC
2	10/20	Adult	Unknown	9	1	11.1	0	Wildtype/non-VOC
3	11/20	Adult	Unknown	18	0	0.0	0	Wildtype/non-VOC
4	11/20	Child	20	14	0	0.0	0	Wildtype/non-VOC
5	12/20	Child	Unknown	12	0	0.0	0	Wildtype/non-VOC
6	01/21	Adult	32	23	0	0.0	1	Unknown
7	01/21	Child	16	13	1	7.7	0	Wildtype/non-VOC
8	01/21	Child	Unknown	7	0	0.0	0	Unknown
9	01/21	Adult	10	8	0	0.0	1	Wildtype/non-VOC
10	02/21	Adultb	17	12	3	25.0	0	Wildtype/non-VOC
11	02/21	Childb,c	Unknown	11	4	36.4	0	VOC-Alpha
12	02/21	Child	16	9	0	0.0	0	VOC-Alpha
13	02/21	Adult	12	10	0	0.0	0	VOC-Alpha
14	02/21	Child	16	5	0	0.0	1	Wildtype/non-VOC
15	02/21	Child	Unknown	15	0	0.0	0	VOC-Alpha
16	02/21	Child	27	18	0	0.0	0	VOC-Alpha
17	03/21	Child	20	7	0	0.0	0	VOC-Alpha
18	03/21	Adult	12	7	0	0.0	0	Unknown
19	03/21	Child	25	16	0	0.0	1	VOC-Alpha
20	03/21	Adult	23	13	1	7.7	0	Wildtype/non-VOC
21	03/21	Child	15	9	0	0.0	0	Unknown
22	03/21	Child	26	8	0	0.0	1	VOC-Alpha
23	03/21	Adult	23	14	4	28.6	0	VOC-Alpha
24	03/21	Childb,c	30	14	11	78.6	1d	VOC-Alpha
25	04/21	Child	Unknown	7	0	0.0	2	VOC-Alpha
26	04/21	Childb	29	19	8	42.1	1d	VOC-Alpha
27	05/21	Adult	28	7	0	0.0	1	VOC-Alpha
28	05/21	Adult	12	7	0	0.0	3	VOC-Alpha
29	06/21	Child	21	10	0	0.0	1	Unknown
30	06/21	Child	Unknown	8	0	0.0	3	VOC-Alpha
Total	–	–	448	343	33	9.6e	17	–

^a7 siblings of primary cases were excluded (6 of them were tested positive).

^bThe primary case was not the index case.

^cThe index case was an adult, the primary case a child.

^dThe person was also tested positive on SARS-CoV-2.

^ePooled secondary attack rate (33 of 343 participating close contacts were tested positive).