Ko 2021.

Study characteristics
Patient Sampling	Purpose: Diagnosis of current acute and convalescent infection Design: Single‐group study to estimate sensitivity only [1] Confirmed COVID cases (51 samples from 29 patients) Recruitment: Not stated Prospective or retrospective: Unclear Sample size: 52 (52) Further detail: Patients with confirmed SARS‐CoV‐2 infections by RT‐PCR. Nothing else stated
Patient characteristics and setting	Setting: Tertiary care hospitals (8 inpatients) or life treatment centre (21 outpatients) Location: Not stated Country: Korea Dates: Not stated Symptoms and severity: 8 pneumonic COVID‐19 patients (hospitalised); 21 mild febrile without pneumonia. Demographics: 17 female, 12 male Age range 23‐80 years Mild febrile (n = 21): 8 (38.1%) male; mean age 32.2 years Exposure history: Not stated Non‐Covid group 1: NA
Index tests	Test name: Not stated Manufacturer: Wells Bio Inc., Seoul, Korea Antibody: IgG, IgM Antigen target: SARS‐CoV‐2 spike‐protein Evaluation setting: POCT, unclear how used Test method: Lateral flow immunoassay principle Timing of samples: Range 4‐56 days pso 4‐6 days pso: 3/52 7‐13 days pso: 6/52 14‐20 days pso: 6/52 21‐27 days pso: 10/52 28+ days pso: 27/52 Samples used: Serum (also used plasma and whole blood for evaluation of test performance according to the types of blood specimens; but this experiment was only done in 2 patients) Test operator: Not stated (test results were interpreted at the time of test and confirmed by the 2 investigators' agreement based on pictures) Definition of test positivity: 1) positive, if the IgG or IgM band showed similar intensity with the control band; 2) weakly positive, if the IgG or IgM band was clearly visible, but much fainter than the control band; 3) very weakly positive, if the IgG or IgM band was visible with very faint intensity; and 4) negative, if the IgG or IgM band was invisible, while the control band was visible. Test results were interpreted at the time of test, and finally confirmed by the two investigators’ agreement (J.‐H.K. and K.R.P) based on the pictures. Blinding reported: No (cases only) Threshold predefined: Yes, visual‐based
Target condition and reference standard(s)	Reference standard: confirmed by RT‐PCR Samples used: Not stated Timing of reference standard: Not stated Blinded to index test: yes, prior index test Incorporated index test: no Definition of non‐COVID cases: NA Samples used: NA Timing of reference standard: NA Blinded to index test: NA Incorporated index test: NA
Flow and timing	Time interval between index and reference tests: Not stated All patients received same reference standard: yes Missing data: Not stated Uninterpretable results: Weakly positive and very weakly positive bands were classed as positive. Indeterminate results: Weakly positive and very weakly positive bands were classed as positive. Unit of analysis: Samples
Comparative
Notes	Funding: None received Wells Bio Inc., Seoul, Korea for donated pilot kits Publication status: Published paper (Short communication) Source: Journal of Microbiology, Immunology and Infection Author COI: The authors declared that they had no conflict of interest.
Methodological quality
Item	Authors' judgement	Risk of bias	Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?	Unclear
Was a case‐control design avoided?	No
Did the study avoid inappropriate exclusions?	Unclear
Did the study avoid inappropriate inclusions?	Yes
Could the selection of patients have introduced bias?		High risk
Are there concerns that the included patients and setting do not match the review question?			High
DOMAIN 2: Index Test (All tests)
DOMAIN 2: Index Test (Antibody tests)
Were the index test results interpreted without knowledge of the results of the reference standard?	No
If a threshold was used, was it pre‐specified?	Yes
Could the conduct or interpretation of the index test have introduced bias?		High risk
Are there concerns that the index test, its conduct, or interpretation differ from the review question?			Unclear
DOMAIN 3: Reference Standard
Is the reference standards likely to correctly classify the target condition?	Yes
Were the reference standard results interpreted without knowledge of the results of the index tests?	Yes
The reference standard does not incorporate the index test	Yes
Could the reference standard, its conduct, or its interpretation have introduced bias?		Low risk
Are there concerns that the target condition as defined by the reference standard does not match the question?			High
DOMAIN 4: Flow and Timing
Was there an appropriate interval between index test and reference standard?	Unclear
Did all patients receive the same reference standard?	Yes
Were all patients included in the analysis?	Unclear
Did all participants receive a reference standard?	Yes
Were results presented per patient?	No
Could the patient flow have introduced bias?		High risk