Weidner 2020 [A].

Study characteristics
Patient Sampling	Purpose: Sensitivity for identification of previous disease Design: Single‐group study estimating sensitivity Used serum samples from convalescent plasma donors with Nucleic Acid Test (NAT)‐confirmed COVID‐19 (n = 100) Recruitment: Unclear Prospective or retrospective: Retrospective Sample size: 100 (100)
Patient characteristics and setting	Setting: Convalescent plasma donors Location: Austrian Red Cross, Blood Service for Vienna, Lower Austria and Burgenland, Vienna Country: Austria Dates: Not stated Symptoms and severity: Severity: 93/100 (93%): mild or no symptoms (WHO class 1‐2); 6/100 (6%): moderate‐severe symptoms (WHO class 3‐6); no details on 1 individual. Reported symptoms: 63% fever, 48% headache, 44% body aches, 43% loss of taste and smell, 40% cough, 31% fatigue, 23% gastrointestinal symptoms, 29% sore throat Demographics: Age range: 18‐66 y; age, median (SD): 47 y (12.7); sex: 61/100 (61%) male Exposure history: Not stated
Index tests	Test name: [A] Euroimmun SARS‐CoV‐2 IgG ELISA [B] Wantai SARS‐CoV‐2 Ab ELISA [C] Roche Elecsys Anti‐SARS‐CoV‐2 [D] LIAISON® SARS‐CoV‐2 S1/S2 IgG [E] MEDsan COVID‐19 IgM/IgG Rapid Test [F] Wantai SARS‐CoV‐2 Ab Rapid Test Manufacturer: [A] Euroimmun, Lübeck, Germany [B] Wantai Biological Pharmacy, Beijing, China [C] Roche Diagnostics, Rotkreuz, Switzerland [D] DiaSorin S.p.A., Saluggia, Italy [E] MPC International S.A., Luxemburg [F] Wantai Biological Pharmacy, Beijing, China Antibody: [A] IgG [B] IgM [C] Total antibodies [D] IgG [E] IgM, IgG [F] Total antibodies Antigen target: [A] S1 domain of the spike‐protein [B] Not stated [C] N‐protein [D] S1 and S2 domains of the spike‐protein [E] Not stated [F] Not stated Evaluation setting: [A]‐[E]: Lab test, done in lab [F]: POC test, unclear if used as POC Test method: [A] [B]: Enzyme‐linked immunosorbent assay (ELISA) [C]: Electrochemilumescence sandwich assay (ECLIA) [D]: Chemiluminescence immunoassay (CLIA) [E], [F]: Lateral flow assay Timing of samples: Samples collected between 26 and 61 days pso (median 47 days, standard deviation 6.6 days) Samples used: Serum, plasma Test operator: Not stated ELISA tests performed at the Center for Virology, Medical University of Vienna; CLIA test performed by Department for Blood Group Serology and Transfusion Medicine, Medical University Graz. Sounded like lab personal for [A]‐[E] Definition of test positivity: [A]: Positive if ratio >= 1.1; borderline if ratio 0.8‐1.09; negative if ratio < 0 [B]: Positive if ratio > 1.0 (the cut‐off is calculated as the mean of three negative controls (minimum 0.03) plus 0.16). [C]: Positive if COI >= 1 [D]: Positive if >= 15 AU/mL; equivocal if 12‐14.9 AU/mL; negative if < 12 AU/mL [E], [F]: Visual‐based (read after 15 min and classified according to their strength, from 0 to 4+. 0 is negative and 4+ corresponds to an intensity equivalent to the control line. A picture card was used to standardise interpretation of the result) Blinding reported: Not stated Threshold predefined: [A]‐[F]: Yes, as per manufacturer
Target condition and reference standard(s)	Reference standard: positive PCR test for COVID‐19 Samples used: Nasopharyngeal swabs or pharyngeal swabs Timing of reference standard: Not stated Blinded to index test: Yes Incorporated index test: No
Flow and timing	Time interval between index and reference tests: Not stated All patients received same reference standard: Unclear ‐ multiple assays were likely used Missing data: Yes: 2 for test [A], 1 for test [C], 1 for test [E], 2 for test [F] Uninterpretable results: No Indeterminate results: yes (classed as TPs) [A] 2 borderline or equivocal results (ID) [D] 5 ID Unit of analysis: Patients
Comparative
Notes	Funding: None reported (This research did not receive any specific grant from funding agencies in the public, commercial, or not‐for‐profit sectors) Publication status: Published paper Source: Academic journal (Journal of Clinical Virology) Author COI: Two authors are employees of Baxter AG, a Takeda company and have Takeda stock 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?	Unclear
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?	Unclear
Were all patients included in the analysis?	Yes
Did all participants receive a reference standard?	No
Were results presented per patient?	Yes
Could the patient flow have introduced bias?		High risk