Bettencourt 2020.

Study characteristics
Patient Sampling	Purpose: Diagnosis of current convalescent‐phase infection Design: Single‐group study to estimate sensitivity [1] Confirmed COVID cases (66 patients) Recruitment: 66 consecutive patients in a real‐life study performed in a hospital partially devoted to COVID‐19 infection Prospective or retrospective: Prospectively Sample size: 66 (66) Further detail: Inclusion: Patients with COVID‐19 disease, which diagnosis was based on clinical evaluation and positive RT ‐PCR SARS‐CoV‐2 identification. Patients in the recovery phase of infection, after the resolution of symptoms and a negative result for the first RT‐PCR test Exclusion: Not stated
Patient characteristics and setting	Setting: Convalescent, hospital inpatients Location: Hospital partially devoted to COVID‐19 infection (Hospital CUF Porto, Faculdade de Medicina da UP, Unidade de Investigação Cardiovascular da FMUP, Portugal) Country: Portugal Dates: Not stated Symptoms and severity: 37 mild disease, 26 moderate disease, 3 severe disease. Overall median time of symptoms was 7 days. Demographics: median age was 59.5 years (44–70). 32/66 women Exposure history: Not stated Non‐Covid group 1: NA
Index tests	Test name: Biozec COVID‐19 IgM/IgG Rapid Test lateral flow immunoassay (LFIA) Manufacturer: Biozec (Inzec) Antibody: IgM and IgG Antigen target: Not stated Evaluation setting: POCT, unclear how performed Test method: Lateral flow immunoassay Timing of samples: Mean 20.5 days (18–23) pso Samples used: Not stated Test operator: Not stated Definition of test positivity: Visually based Blinding reported: Not stated, possibly no as only COVID cases included Threshold predefined: Performed according to the manufacturer’s instructions
Target condition and reference standard(s)	Reference standard: RT‐PCR, threshold not stated 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: NA
Flow and timing	Time interval between index and reference tests: Not stated All patients received same reference standard: yes Missing data: Not stated (no results for IgM reported though) Uninterpretable results: Not stated Indeterminate results: Not stated Unit of analysis: Patients
Comparative
Notes	Funding: Not stated Publication status: Published letter Source: Journal of Infection 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?	Unclear
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?	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?	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