Gao 2020b [C].

Study characteristics
Patient Sampling	See main entry for this study for characteristics and QUADAS‐2 assessment (Gao 2020b [A])
Patient characteristics and setting	See main entry for this study for characteristics and QUADAS‐2 assessment (Gao 2020b [A])
Index tests	Gao 2020b [C] is test [C] from the following entry: Test name: [A] CLIA; [B] GICA; [C] ELISA Manufacturer: Beier Bioengineering Company (Beijing, China) Ab targets: IgG and IgM Antigens used: spike (S) and nucleocapsid (N) proteins of 2019‐nCoV Test method: [A] CLIA; [B] GICA; [C] ELISA Timing of samples: [1] early stage (1‐7 days pso) 10/37 samples (27%), [2] middle stage (8‐14 days pso) 13/37 samples (35%); [3] late stage (14‐24 days pso) 14/37 samples (38%) Samples used: serum Test operators: laboratory staff Definition of test positivity: [A] samples with an concentration ≥ 8 arbitrary unit (AU)/mL were considered positive. [B] Visible line [C] The absorbance at 450 nm (A450 nm) of each well was determined and the cut‐off value was 0.10 + A negative control. A value > cut‐off value was considered a positive result. Blinded to reference standard: NR Threshold predefined: [A] samples with an concentration ≥ 8 arbitrary unit (AU)/mL were considered positive. [B] Positive results showed the appearance of both control line and testing line. [C] The absorbance at 450 nm (A450 nm) of each well was determined and the cut‐off value was 0.10 + A negative control. A value > cut‐off value was considered a positive result.
Target condition and reference standard(s)	See main entry for this study for characteristics and QUADAS‐2 assessment (Gao 2020b [A])
Flow and timing	See main entry for this study for characteristics and QUADAS‐2 assessment (Gao 2020b [A])
Comparative
Notes