Table 2.

Performance characteristics of Orient Gene Biotech LFA and Wantai ELISA in patients with suspected COVID-19 compared with nucleic acid amplification tests as reference standard

	All patients	Time from symptom onset to sample collection <7 days a	Time from symptom onset to sample collection ≥7 days a	p	Non-ICU	ICU	p	CRP <100 mg/L	CRP ≥100 mg/L	p
Orient Gene Biotech LFA
Sensitivity	43/99 (43; 95% CI 34–53)	11/39 (28; 95% CI 14–42)	31/52 (60; 95% CI 46–73)	<0.01	35/83 (42; 95% CI 32–53)	8/16 (50; 95% CI 26–75)	0.56	22/66 (33; 95% CI 22–45)	21/33 (64; 95% CI 47–80)	<0.01
Specificity	126/129 (98; 95% CI 95–100)	39/40 (98; 95% CI 93–100)	48/50 (96; 95% CI 91–100)	0.96	122/124 (98; 95% CI 96–100)	4/5 (80; 95% CI 45–100)	<0.01	109/111 (98; 95% CI 96–100)	17/18 (94; 95% CI 84–100)	0.33
Wantai ELISAb
Sensitivity	59/95 (62; 95% CI 52–72)	19/39 (49; 95% CI 33–64)	38/48 (79; 95% CI 68–91)	<0.01	49/80 (61; 95% CI 51–72)	10/15 (67; 95% CI 43–91)	0.69	36/65 (55; 95% CI 43–68)	23/30 (77; 95% CI 62–92	0.047
Specificity	125/128 (98; 95% CI 95–100)	39/40 (98; 95% CI 93–100)	48/50 (96; 95% CI 91–100)	1.00	121/123 (98; 95% CI 96–100)	4/5 (80; 95% CI 45–100)	0.11	108/110 (98; 95% CI 96–100)	17/18 (94; 95% CI 84–100)	0.37

Abbreviations: CRP, C-reactive protein; ICU, intensive care unit; LFA, lateral flow immunochromatographic assays.

Data are presented in absolute numbers (percentages). Of note, sensitivity was 17/24 (71%) in patients with ≥7 days from symptom onset to sample collection and CRP was ≥100 mg/L.

^aIn some patients time from symptom onset was undetermined or unavailable. In the subgroup of patients with time from symptom onset to sample collection ≥14 days, sensitivity and specificity of the LFA were 9/14 (64%; 95% CI 39%–89%) and 30/32 (94%; 95% CI 85%–100%), respectively, whereas sensitivity and specificity of the ELISA were 6/12 (50%; 95% CI 22%–78%) and 30/32 (94%; 95% CI 85%–100%), respectively.

^b5/228 (2%) samples were unavailable for ELISA.