Rudolf 2020 [A].

Study characteristics
Patient Sampling	Purpose: Diagnosis of current acute‐phase infection or current convalescent‐phase infection Design: Multi‐group study to estimate sensitivity and specificity [1] Confirmed COVID samples (n = 366) [2] Non‐COVID samples [2a] Blood donor samples from influenza seasons 2016/17 and 2017/18 (n = 500) [2b] Samples which tested PCR‐negative for SARS‐CoV‐2 (n = 110) Recruitment: Not stated Prospective or retrospective: Retrospective Sample size: 976 (366) Further detail: Inclusion: [1] Serum of our previously described positive (SERO‐BL‐positive) cohort of study participants testing PCR‐positive for SARS‐CoV‐2 during the initial wave of COVID‐19 infections in the canton of Basel‐Landschaft Switzerland [2a] Blood donor cohort composed of donations from December 2016, February 2017, and February 2018 [2b] Serum of our previously described negative (SERO‐BL‐negative) cohort of study participants testing PCR‐negative for SARS‐CoV‐2 during the initial wave of COVID‐19 infections in the canton of Basel‐Landschaft,2 Switzerland Exclusions not reported.
Patient characteristics and setting	Setting: Convalescent study participants of SERO‐BL‐COVID‐19 Location: Biobank of the Canton Basel‐Landschaft Country: Switzerland Dates: During the first wave of the pandemic in Switzerland Symptoms and severity: Wide range of disease severity; these samples were representative for symptomatic and oligosymptomatic cases. Demographics: Not stated Exposure history: Not stated Non‐Covid group 1: [2a] Pre‐pandemic healthy Source: Blood donor cohort composed of donations from December 2016, February 2017, and February 2018 Characteristics: Blood donor samples from previous flu seasons Non‐Covid group 2: [2a] Current, PCR‐negative Source: Study participants of "COVID‐19 in Baselland Investigation and Validation of Serological Diagnostic Assays and Epidemiological Study of Sars‐CoV‐2 specific Antibody Responses (SERO‐BL‐COVID‐19)", during the first wave of the pandemic in Switzerland Characteristics: PCR‐negative
Index tests	Test name: [A] OnSite™ COVID‐19 IgG/IgM Rapid Test (LOT F0507R1C00) [B] SARS‐CoV‐2 IgM/IgG Antibody Rapid Test (LOT COV1252006A) [C] SimtomaX® Corona Check (LOT GGM20089W) [D] SARS‐CoV‐2 Antibody Lateral Flow Test (LOT 20200428) [E] NTBIO One Step Rapid Test ‐ COVID‐19 IgG/IgM Antibody Test (LOT V02009201) [F] QuickTestCorona™ COVID‐19 IgG/IgM (LOT MC0000102) [G] SARS‐Cov‐2 IgG/IgM Rapid Qualitative Test (LOT X2003602) [H] BIOZEK COVID‐19 IgG/IgM Rapid Test Cassette (LOT BNCP40200080) [I] MEDsan COVID‐19 IgM/IgG Rapid Test (LOT 20200325) [J] SARS‐CoV‐2 IgM/IgG Ab Rapid Test (LOT COV1252003C) [K] The RightSignTM COVID‐19 IgG/IgM Rapid Test Cassette / Lumiratek (LOT COV20040013) Manufacturer: [A] CTK Biotech, Inc. (US) [B] Sure Bio‐tech (USA) Co., Ltd (US) [C] Augurix SA (CH) [D TAmiRNA GmbH (AT) [E] NTBIO® Diagnostics Inc. (CA) [F] MEXACARE GmbH (DE) [G] Xiamen Biotime Biotechnology Co., Ltd. (CN) [H] Inzek International Trading B.V. (NL) [I] MPC International S.A. (LU) [J] Qingdao HIGHTOP Biotech Co., Ltd. (CN) [K] Hangzhou Biotest Biotech Co Ltd (CN) Antibody: [D] IgM/IgG (single band) All other tests: separate lines for IgM and IgG Antigen target: [A] Spike [B] S1, S2, RBD [C] RBD, N‐protein [D] S1 [E] Not stated [F] RBD, N‐protein [G] Not stated [H] Not stated [I] Not stated [J] Spike, N‐protein [K] Spike Evaluation setting: All POCT performed in lab Test method: All lateral flow tests (no details) Timing of samples: wide range of days post‐symptom onset <= 14 days pso 15‐21 days pso > 21 days pso Numbers differed between tests. Samples used: We assayed the Hightop test using whole blood, serum and plasma, while all other tests were assayed using serum and plasma. Test operator: The Hightop [J] and MEDSan [I] assays were characterised at the SwissTPH using the identical biobank and experimental setup as outlined previously. Eight tests were characterised simultaneously at the KUSPO Munchenstein and the Biotime [G} at the FHNW, Muttenz. Definition of test positivity: Presence of bands was visually inspected, and each test was imaged with a digital camera (different models) under standardised lightning conditions. We considered a test valid if its control band was present, and we considered a valid test positive for the respective antibody if the SARS‐CoV‐2 specific IgM, IgG or IgM/IgG band was detected in the sample. Blinding reported: Unclear Threshold predefined: Yes, visual‐based
Target condition and reference standard(s)	Reference standard: [1] PCR‐positive for SARS‐CoV‐2 Samples used: Not stated Timing of reference standard: Not stated Blinded to index test: Yes, prior to index test Incorporated index test: No Definition of non‐COVID cases: [2a] Pre‐pandemic [2b] PCR‐negative for SARS‐CoV‐2 Samples used: [2a] Pre‐pandemic [2b] Not stated Timing of reference standard: [2a] Pre‐pandemic [2b] Not stated Blinded to index test: Yes, prior to index test Incorporated index test: no
Flow and timing	Time interval between index and reference tests: Not stated All patients received same reference standard: no Missing data: Yes (not all samples tested with all index tests; time split <= 14 days pso not eligible for our review) Uninterpretable results: Not stated Indeterminate results: No intermediate range Unit of analysis: Not stated
Comparative
Notes	Funding: The Swiss Red Cross financed all the used LFA except for the Hightop and Biotime assays. The Hightop was purchased by the canton Basel‐Landschaft and the Biotime was provided by the Swiss importer. FR is funded by the NCCR ’Molecular Systems Engineering’. Publication status: Pre‐print (not peer reviewed) Source: medRxiv preprint Author COI: Not stated
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?			Unclear
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?	Yes
Were results presented per patient?	Unclear
Could the patient flow have introduced bias?		High risk