Bartolini 2020 [A].

Study characteristics
Patient Sampling	Purpose: Evaluation of two different immunochromatographic (IC) rapid tests for detection of IgG and IgM against SARS‐CoV‐2 Design: RT‐PCR‐positive asymptomatic/mildly symptomatic healthcare workers (n = 151) Recruitment: All 151 RT‐PCR‐positive cases from a mass screening of 10,945 asymptomatic/mildly symptomatic healthcare workers at the Local Health Unit of Bologna taking part in a seroprevalence study (surveillance programme established by the Emilia‐Romagna Region). Due the contacts caused by the type of work done, some of them were considered much more exposed to risk of infection; for this reason they had previously been submitted to RT‐PCR. Prospective or retrospective: Prospectively in a mass screening programme (surveillance programme). The samples were collected after informed consent was given. Sample size: 151 (151) of which 35 (35) were tested with test [1] and 116 (116) tested with test [2] Further detail: RT‐PCR‐positive
Patient characteristics and setting	Setting: Healthcare workers Location: Local Health Unit of Bologna Country: Italy Dates: Serological tests done between 3rd to 27th of April 2020 RT‐PCR tests done 0‐45 days before Symptoms and severity: asymptomatic/mildly symptomatic Demographics: Not stated Exposure history: Not stated (Due the contacts caused by the type of work done, some of them were considered much more exposed to risk of infection) Non‐Covid group 1: NA
Index tests	Test name: [1] KHB® Diagnostic Kit for SARS‐CoV‐2 IgM/IgG Antibody (Colloidal Gold) [2] Cellex qSARS‐CoV‐ 2 IgG/IgM Cassette Rapid Test Manufacturer: Not stated Antibody: [1] IgG. IgM [2] IgG. IgM Antigen target: Not stated ‐ SARS‐CoV‐2 conjugate Evaluation setting: [1] POC, used in a laboratory [2] POC, used in a laboratory Test method: [1] lateral flow chromatographic immunoassay (Colloidal Gold) [2] lateral flow chromatographic immunoassay Timing of samples: 0‐45 days after positive RT‐PCR ([1]/[2]) Samples used: plasma Test operator: Laboratory personnel Definition of test positivity: Both tests: The presence of the captured immunocomplex is visible due to its precipitation in a coloured red band. Blinding reported: No ‐ all samples RT‐PCR‐positive Threshold predefined: Yes, as per manufacturer, visual
Target condition and reference standard(s)	Reference standard: SARS‐CoV‐2 RT‐PCR Samples used: nasopharyngeal or oropharyngeal samples Timing of reference standard: Not stated (mostly asymptomatic patients) Blinded to index test: Yes ‐ prior Incorporated index test: No Definition of non‐COVID cases: NA
Flow and timing	Time interval between index and reference tests: 0‐45 days All patients received same reference standard: Yes Missing data: Not stated Uninterpretable results: Not stated Indeterminate results: Not stated Unit of analysis: Patients
Comparative
Notes	Funding: Not stated Publication status: Pre‐print (not peer reviewed) Source: medRxiv preprint doi: https://doi.org/10.1101/2020.05.28.20116046 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?	Yes
Was a case‐control design avoided?	No
Did the study avoid inappropriate exclusions?	Yes
Did the study avoid inappropriate inclusions?	Yes
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?	Yes
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?		Unclear risk