Sweeney 2020.

Study characteristics
Patient Sampling	Purpose: Two‐group study to estimate sensitivity and specificity for diagnosis of acute and previous Covid‐19 Design: [1] PCR‐confirmed SARS‐CoV‐2 positive individuals (n = 301) [2] Pre‐pandemic stored serum samples (n = 200) [3] Pre‐pandemic stored acute and convalescent confounder samples from individuals with a range of viral, bacterial and fungal pathogens (n = 100) Recruitment: Unclear Prospective or retrospective: Retrospective Sample size: 601 (301) Further detail: No more details available
Patient characteristics and setting	Setting: Unclear Location: Guy's and St Thomas' NHS Foundation Trust, London Country: UK Dates: Unclear Symptoms and severity: Unclear Demographics: Unclear Exposure history: Unclear Non‐Covid group 1: Pre‐pandemic stored samples Source: 43525 Characteristics: Unclear Non‐Covid group 2: Pre‐pandemic confounder samples Source: Not stated Characteristics: Cytomegalovirus (n = 8), Epstein‐Barr virus (EBV) (n = 10), hepatitis A virus (n = 8), hepatitis B virus (n = 7), hepatitis C virus (n = 5), human immunodeficiency virus (HIV) (n = 9), Kaposi's sarcoma herpesvirus 1/2 (n = 5), measles virus (n = 6), mumps (n = 9), mycobacterium (n = 1), parvovirus (n = 7), pneumocystis pneumonia (n = 4), rubella virus (n = 5), syphilis virus (n = 4), toxoplasma gondii (n = 7), varicella zoster virus (n = 5)
Index tests	Test name: SureScreen LFIA Manufacturer: Surescreen Diagnostics, UK Antibody: IgM/IgG Antigen target: "detecting antibodies to SARS‐CoV‐2 spike proteins" Evaluation setting: POC, used in the laboratory Test method: Lateral flow immunoassay Timing of samples: [1] 14+ days post‐onset of symptoms: 301/301 (100%), of which: 14‐19 days post‐onset of symptoms: 97/301 (32%) 20+ days post‐onset of symptoms: 204/301 (68%) Samples used: Serum Test operator: Laboratory staff Definition of test positivity: 2 independent operators evaluating the result. A detectable band of either IgM or IgG (or both) was reported to the clinician as “antibodies detected". Blinding reported: Unclear Threshold predefined: yes, visual‐based test
Target condition and reference standard(s)	Reference standard: RT‐PCR (AusDiagnostics); threshold not stated (reference PHE 2020 rapid assessment) Samples used: Unclear Timing of reference standard: Not stated Blinded to index test: Yes, occurred before Incorporated index test: No Definition of non‐COVID cases: Pre‐pandemic Samples used: None Timing of reference standard: NA Blinded to index test: Yes Incorporated index test: No
Flow and timing	Time interval between index and reference tests: Unclear All patients received same reference standard: No Missing data: Nothing mentioned Uninterpretable results: Nothing mentioned Indeterminate results: Nothing mentioned Unit of analysis: Patients
Comparative
Notes	Funding: King’s Together Rapid COVID‐19 Call awards to KJD, SJDN and RMN. MRC Discovery Award MC/PC/15068 to SJDN, KJD and MHM. National Institute for Health Research (NIHR) Biomedical Research Centre based at Guy's and St Thomas' NHS Foundation Trust and King's College London, programme of Infection and Immunity to MHM and JE. AWS and CG were supported by the MRC‐KCL Doctoral Training Partnership in Biomedical Sciences. GB was supported by the Wellcome Trust. SA was supported by an MRC‐KCL Doctoral Training Partnership in Biomedical Sciences industrial Collaborative Award in Science & Engineering (iCASE) in partnership with Orchard Therapeutics. NK was supported by the Medical Research Council. SP, HDW and SJDN were supported by a Wellcome Trust Senior Fellowship. Fondation Dormeur, Vaduz for funding equipment (KJD). Development of SARS‐CoV‐2 reagents (RBD) was partially supported by the NIAID Centers of Excellence for Influenza Research and Surveillance (CEIRS) Publication status: Pre‐print (not peer reviewed) Source: medRxiv Author COI: All authors have completed the ICMJE uniform disclosure form at www.icmje.org/coi_disclosure.pdf and declared: no support from any organisation for the submitted work; no financial relationships with any organisations that might have an interest in the submitted work in the previous three years; 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?	No
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?	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?	No
Were all patients included in the analysis?	Yes
Did all participants receive a reference standard?	Unclear
Were results presented per patient?	Yes
Could the patient flow have introduced bias?		High risk