Kohmer 2020b [A].

Study characteristics
Patient Sampling	Purpose: Assessment of clinical performance of multiple COVID‐19 tests Design: Multi‐group study estimating both sensitivity and specificity Group [1]: Symptomatic PCR‐confirmed COVID‐19 cases (n = 45) Group [2]: Other known infections (other coronaviruses, EBV, CMV) including some pre‐pandemic (n = 37); review team excluded 6 samples with serologically confirmed SARS‐COV‐2 infection based on PRNT) Recruitment: Unclear Prospective or retrospective: Not stated but likely retrospective Sample size: 82 (45) Further detail: No more details available
Patient characteristics and setting
Index tests	Test name: [A] SARS‐CoV‐2 IgG [B] Elecsys Anti‐SARS‐CoV‐2 [C] Liaison SARS‐CoV‐2 S1/S2 IgG [D] COVID‐19 VIRCLIA IgG MONOTEST [E] Anti‐SARS‐CoV‐2 ELISA (IgG) [F] Virotech SARS‐CoV‐2 ELISA IgG Manufacturer: [A] Abbott GbmH, Wiesbaden, Germany [B] Roche Diagnostics International AG, Rotkreuz, Switzerland [C] DiaSorin Deutschland GmbH, Dietzenbach, Germany [D] Vircell Spain S.L.U., Granada, Spain [E] Euroimmun, Lubeck, Germany [F] Virotech Diagnostics GmbH, Russelsheim, Germany Antibody: All tests except for [B]: IgG [B]: total antibody Antigen target: [A] N‐protein [B] N‐protein [C] S1 and S2‐protein [D] S1 and N‐protein [E] S1‐protein [F] N‐protein Evaluation setting: All lab tests, done in lab Test method: [A] Chemiluminescent microparticle assay (CMIA) [B] Electrochemiluminescence immunoassay (ECLIA) [C] Chemiluminescent immunoassay (CLIA) [D] Chemiluminescent immunoassay (CLIA) [E] Enzyme‐linked immunosorbent assay (ELISA) [F] Enzyme‐linked immunosorbent assay (ELISA) Timing of samples: No info regarding time since symptom onset. Group [1A]: collected 2‐49 days after PCR‐positive test. Not stated for the others. Samples used: Serum or plasma Test operator: Not stated Definition of test positivity: [A] positive if index S/C >= 1.4 [B] positive if signal sample/cut‐off >= 1.0 [C] positive if >= 15 AU/mL; equivocal if 12‐15 AU/mL [D] positive if AI >= 1.6; equivocal if AI 1.4‐1.6 [E] positive if ratio >= 1.1; equivocal if ratio 0.8‐1.1 [F] positive if Index > 1.1; equivocal if Index 0.9‐1.1 Blinding reported: Unclear Threshold predefined: Yes, as per manufacturer. However, specified they allocated Euroimmun equivocal as negative (post hoc)
Target condition and reference standard(s)	Reference standard: Groups [1A] and [1B]: PCR (not further specified) Samples used: Not stated Timing of reference standard: Not stated Blinded to index test: Yes (done earlier) Incorporated index test: No Definition of non‐COVID cases: Group [2] and [3]: No testing Samples used: Group [2] and [3]: NA Timing of reference standard: Group [2] and [3]: NA Blinded to index test: Group [2] and [3]: NA Incorporated index test: Group [2] and [3]: NA
Flow and timing	Time interval between index and reference tests: Group [1A]: index tests done 2 to 49 days after PCR‐positivity (unknown for 4 cases) All patients received same reference standard: No Missing data: None (but not all index tests were used on all samples to assess specificity) Uninterpretable results: Yes, for [B]: 2 "equivocal" results, considered as negative Indeterminate results: None Unit of analysis: Patients
Comparative
Notes	Funding: None reported Publication status: Published article Source: Academic journal Author COI: One author received speaker’s fee from Euroimmun (manufacturer of one of the index tests).
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?	Unclear
If a threshold was used, was it pre‐specified?	Yes
Could the conduct or interpretation of the index test have introduced bias?		Unclear risk
Are there concerns that the index test, its conduct, or interpretation differ from the review question?			Low concern
DOMAIN 3: Reference Standard
Is the reference standards likely to correctly classify the target condition?	Unclear
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?		Unclear 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?	No
Were all patients included in the analysis?	No
Did all participants receive a reference standard?	Unclear
Were results presented per patient?	Yes
Could the patient flow have introduced bias?		High risk