Assennato 2020.

Study characteristics
Patient Sampling	Single‐group study to estimate sensitivity and specificity: ‐ samples from symptomatic individuals with suspected COVID‐19 sent for routine laboratory diagnosis; supplied via PHE (n = 172) Recruitment: not stated Prospective or retrospective: retrospective Number of samples (samples with confirmed SARS‐CoV‐2): 172 (88)
Patient characteristics and setting	Setting: not stated; supplied by PHE Location: PHE, Cambridge Laboratory (samples from East of England) Country: UK Dates: not stated Symptoms and severity: symptomatic; no further details Demographics: not stated Exposure history: not stated
Index tests	Test name: SAMBA II SARS‐CoV‐2 Test Manufacturer: Diagnostics for the Real World Antigen target: ORF1ab, N2 Antibody: N/A Test method: rapid PCR Samples used: combined nose and throat swab samples, provided as VTM Transport media: samples diluted 1:2 with SAMBA SCoV buffer Sample storage: not stated Test operator: not stated; presume laboratory staff Definition of test positivity: as per manufacturer; either target present Blinding reported: yes; states that samples were rendered anonymous and provided blinded for the purpose of test validation Timing of samples: not stated
Target condition and reference standard(s)	Reference standard: RT‐PCR; (1) Cambridge RdRp gene (Wuhan) assay on the Rotor gene Q real‐time PCR assay routinely used by PHE; Ct ≤ 36 considered positive. (2) Samples also tested with the PHE Colindale (Reference Laboratory) assay Definition of non‐COVID cases: Single RT‐PCR negative Genetic target(s): (1) RdRp, E gene, (2) RdRp 'different region' Samples used: combined nose and throat swab in VTM; same as for index test Timing of reference standard: not stated; Cambridge assay seems to have been part of routine testing near to time of sample collection; not clear if Colindale assay was at a later date after a period of storage Blinded to index test: not stated but seems yes for Cambridge assay Incorporated index test: no
Flow and timing	Time interval between index and reference tests: not stated; seems likely reference was carried out for routine diagnostic testing All participants received same reference standard: yes (all samples underwent both RT‐PCR tests) Missing data: none reported, no participant flow diagram reported Uninterpretable results: none reported Indeterminate results (index test): 3 FP and 1 FN result retested using SAMBA‐II; same results obtained on repeat Indeterminate results (reference standard): 3 FP and 1 FN result were re‐tested ‐ all 3 FPS found to be borderline positive for ≥ 1 target gene on either Colindale or Cambridge (Wuhan) test (reclassified as TP) ‐ the FN result remained positive on both RT‐PCR assays Unit of analysis: refers to participants rather than samples
Comparative
Notes	Funding: RKG is funded by Wellcome Senior Fellowship In Clinical Science award no WT108082AIA Publication status: preprint Source: medRxiv Author COI: no COI statement reported; 3 co‐authors are affiliated to test manufacturer
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?	Yes
Did the study avoid inappropriate exclusions?	Unclear
Did the study avoid inappropriate inclusions?	Unclear
Could the selection of patients have introduced bias?		Unclear risk
Are there concerns that the included patients and setting do not match the review question?			Unclear
DOMAIN 2: Index Test (Antigen tests)
DOMAIN 2: Index Test (Rapid molecular tests)
Were the index test results interpreted without knowledge of the results of the reference standard?	Yes
If a threshold was used, was it pre‐specified?	Yes
Could the conduct or interpretation of the index test have introduced bias?		Low 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?	No
Were the reference standard results interpreted without knowledge of the results of the index tests?	Yes
Reference standard does not incorporate result of index test?	Yes
Could the reference standard, its conduct, or its interpretation have introduced bias?		High 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?	Yes
Did all patients receive the same reference standard?	Yes
Were all patients included in the analysis?	Unclear
Did all participants receive a reference standard?	Yes
Were results presented per patient?	Yes
Could the patient flow have introduced bias?		Unclear risk