Muecksch 2020 [A].

Study characteristics
Patient Sampling	Purpose: Investigate performance of 4 SARS‐CoV‐2 serological assays in diagnosing prior infection Design: Single‐group study, sensitivity only [1] Prior RT‐PCR‐diagnosed SARS‐CoV‐2 positive (non‐hospitalised, relatively mildly symptomatic) Recruitment: Unclear, NHS Lothian Prospective or retrospective: Retrospective Sample size: 97 (97) Further detail: Inclusion criteria: Individuals with RT‐PCR diagnosed SARS‐CoV‐2 infection that did not require hospitalisation. Recruits surveyed to determine date of positive PCR test, date of onset of symptoms and if they required hospitalisation. 97 patients who were not hospitalised were included. Exclusion criteria: Not stated
Patient characteristics and setting	Setting: NHS outpatient clinics Location: Unclear, NHS Lothian (Abbott and Diasorin), NHS Lanarckshire (Roche), NHS Tayside (Siemens Atellica) NHS Lothian BioResource Country: United Kingdom (Scotland) Dates: Not stated Symptoms and severity: Mildy symptomatic, 70% of participants reported at least one of fever, cough or anosmia. Demographics: Mean age 44.2 years (21‐65 y), 70 female (72%) participants Exposure history: Not stated
Index tests	Test name: [A] Abbott SARS‐CoV‐2 IgG assay [B] DiaSorin SARS‐CoV‐2 IgG assay [C] Roche Anti‐SARS‐CoV total antibody assay [D] Siemens SARS‐CoV‐2 total antibody assay Manufacturer: [A] Abbott Laboratories, Illinois, USA [B] DiaSorin S.p.A., Saluggia, Italy [C] Roche Diagnostics, Rotkreuz, Switzerland [D] Siemens Healthcare Ltd, Surrey, United Kingdom Antibody: [A] IgG [B] IgG [C] total antibody [D] total antibody Antigen target: [A] N‐protein [B] S‐protein [C] N‐protein [D] RBD of S‐protein Evaluation setting: Laboratory Test method: [A] CMIA [B] CMIA [C] ECLIA [D] CLIA Timing of samples: Visit [1] (baseline) avg. 40.8 days post‐PCR +ve (range 24‐61 days), Visit [2] (two weeks post‐baseline) avg. 55.1 days post‐PCR +ve (range 40‐79 days), Visit [3] (four weeks post‐baseline) avg. 69.8 days post‐PCR +ve (range 55‐95 days), Visit [4] (8 weeks post‐baseline) avg. 98.4 days (85‐110 days) Samples used: Convalescent serum Test operator: Laboratory staff [NHS Lothian (Abbott and Diasorin), NHS Lanarckshire (Roche), NHS Tayside (Siemens Atellica)] Definition of test positivity: (All the assays generate a qualitative positive/negative result based on assay‐dependent signal thresholds. Each assay gives a qualitative positive or negative result, based on assay specific thresholds) [A] S/C [B] AU/mL [C] COI [D] AU Blinding reported: Unclear Threshold predefined: Not stated, possibly yes ("assay specific thresholds", unclear if this meant manufacturer recommended thresholds)
Target condition and reference standard(s)	Reference standard: RT‐PCR Samples used: Not stated Timing of reference standard:Unclear Blinded to index test: Yes Incorporated index test: no Definition of non‐COVID cases: NA
Flow and timing	Time interval between index and reference tests: 24‐110 days post‐PCR +ve All patients received same reference standard: Yes Missing data: Not stated (97 * 3 = 291 samples + 28 with a 4th sample = 319 samples, there seemed to be no samples missing but no flow diagram provided) Uninterpretable results: Not stated Indeterminate results: Not stated Unit of analysis: Samples
Comparative
Notes	Funding: This work was supported by the NHS and Grants from the National Institutes of Allergy and infectious Diseases R37AI640003 (to PDB) and R01AI078788 (to TH). There were no study sponsors. The funders played no role in the design, analysis or reporting of this research. Publication status: Pre‐print (not peer reviewed) Source: Pre‐print medRxiv Author COI: Authors declared no support from any organisation or financial relationships with any organisations that might have an interest in the submitted work in the previous three years, or no other relationships or activities that could appear to have influenced the submitted work.
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?	Unclear
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?			Low concern
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?	Yes
Did all participants receive a reference standard?	Unclear
Were results presented per patient?	No
Could the patient flow have introduced bias?		High risk