Table 1:

Performance of rapid antigen detection tests in the participant groups

RADT (nasal)	Positive	Results, no. of participants		Invalid	Clinical performance of RADTs		Specificity, % (95% CI)
		PCR (gargle)			Sensitivity, % (95% CI)
		Negative	Equivocal or weak positive		Excluding equivocal or weak positive	Including equivocal or weak positive
Asymptomatic students *
Positive	7	1	0	0	n = 17 41.2 (21.6–64.0)	n = 26 26.9 (13.7–46.1)	100§ (99.9–100)
Negative	10	5549	9	7
Invalid	0	0	0	0
Asymptomatic students considered exposed contacts of positive index cases †
Positive	4	6	0	0	n = 14 28.6 (8.4–58.1)	n = 15 26.7 (7.8–55.1)	99.6 (99.1–99.9)
Negative	10	1470	1	0
Invalid	0	0	0	0
Symptomatic students ‡
Positive	10	0	0	0	83.3 (51.6–97.9)	NA	100.0 (98.4–100.0)
Negative	2	223	0	0
Invalid	0	0	0	0
Asymptomatic staff members
Positive	0	1	0	0	NA	NA	99.9 (99.3–100.0)
Negative	0	775	0	2
Invalid	0	0	0	0
Asymptomatic staff members considered exposed contacts of positive index cases
Positive	0	0	0	0	NA	NA	100.0 (94.1–100.0)
Negative	0	61	0	0
Invalid	0	0	0	0
Symptomatic staff members
Positive	1	0	0	0	50.0 (1.3–98.7)	NA	100.0 (94.3–100.0)
Negative	1	62	0	0
Invalid	0	0	0	0

Note: CI = confidence interval, NA = not applicable, PCR = polymerase chain reaction, RADT = rapid antigen detection test.

^*Prevalence of SARS-CoV-2 infection, based on PCR results (including equivocal and weakly positive results): 0.30% (95% CI 0.18%–0.49%).

^†Prevalence of SARS-CoV-2 infection, based on PCR results (including equivocal and weakly positive results): 0.7% (95% CI 0.5%–1.6%).

^‡Prevalence of SARS-CoV-2 infection, based on PCR results (including equivocal and weakly positive results): 5.1% (95% CI 2.65%–8.71%).

^§The specificity of RADT in asymptomatic students was 99.98% when adjusted to 2 decimal places.