Table 2.

Discordance Between Rapid Antigen and Follow-Up PCR Tests for Antigen Tests Done during a Facility Outbreak vs No Outbreak

	No Outbreak			Outbreak
	Overall	Symptomatic	Asymptomatic	Overall	Symptomatic	Asymptomatic
Total antigen tests, n	65,442	1121	64,321	105,627	1931	103,696
Antigen tests with a follow-up PCR test, n (%)	3143 (4.8%)	184 (16.4%)	2959 (4.6%)	11,577 (11.0%)	439 (22.7%)	11,138 (10.7%)
Negative antigen tests with positive follow-up PCR test, n	11	0	11	797	58	739
% of total antigen tests with discordant PCR	0.02%	0%	0.02%	0.8%	3.0%	0.7%
% of repeated tests with discordant PCR	0.3%	0%	0.4%	6.9%	13.2%	6.6%
Positive antigen tests with negative follow-up PCR test, n	16	0	16	296	13	283
% of total antigen tests with discordant PCR	0.02%	0%	0.02%	0.3%	0.7%	0.3%
% of repeated tests with discordant PCR	0.5%	0%	0.5%	2.6%	3.0%	2.5%

All vendors, repeat PCR within 1 day. Symptomatic vs asymptomatic determined based on whether the resident had new onset symptoms in the 5 days prior to testing. Outbreak is defined as 1+ new resident SARS-CoV-2 case(s) in the facility in the 14 days prior to the test. Data as of January 10, 2021. Note, total antigen tests here = 171,069 vs. 171,280 in Table 1 due to some missing daily census data needed to determine outbreak status at time of testing.