Table 2.

Number of PCR-positive participants (secondary cases), their contacts (secondary contacts), and number of tertiary cases identified in NHSTT records

	Self-isolation group	DCT group	Total
Number of PCR-positive cases among study participants (secondary cases)	2364	2330	4694
Number of PCR-positive cases among study participants (secondary cases) identified in NHSTT	2390	2358	4748
Number of secondary cases with NHSTT secondary contacts	1953	1862	3815
Number of secondary cases with NHSTT household secondary contacts	1927	1823	3750
Number of secondary cases with NHSTT non-household secondary contacts	214	233	447
Number of secondary contacts	5219	5191	10 410
Number of household secondary contacts	4651	4545	9196
Number of non-household secondary contacts	568	646	1214
Number of tertiary cases	393	325	718
Number of tertiary cases from household contacts	373	306	679
Number of tertiary cases from non-household contacts	20	19	39
Number of secondary contacts per participant case (all cases)	2·2	2·2	2·2
Number of secondary contacts per participant case (cases with contacts)	2·7	2·8	2·7
Number of household secondary contacts per participant case (all cases)	2·0	1·9	1·9
Number of household secondary contacts per participant case (cases with household contacts)	2·4	2·5	2·5
Number of non-household secondary contacts per participant case (all cases)	0·2	0·3	0·3
Number of non-household secondary contacts per participant case (cases with non-household secondary contacts)	2·7	2·8	2·7
Number of tertiary cases per NHSTT secondary case	0·2	0·1	0·2
Number of tertiary cases per secondary case via household secondary contact	0·2	0·1	0·1
Number of tertiary cases per secondary case via non-household secondary contact	0·01	0·01	0·01

Where a case had multiple records, all were included. DCT=daily contact testing. NHSTT=NHS Test and Trace.