Validation of a commercially available SARS-CoV-2 serological immunoassay.
Clin Microbiol Infect
; 26(10): 1386-1394, 2020 Oct.
Article
in English
| MEDLINE | ID: covidwho-628848
Preprint
This scientific journal article is probably based on a previously available preprint. It has been identified through a machine matching algorithm, human confirmation is still pending.
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This scientific journal article is probably based on a previously available preprint. It has been identified through a machine matching algorithm, human confirmation is still pending.
See preprint
ABSTRACT
OBJECTIVES:
To validate the diagnostic accuracy of a Euroimmun SARS-CoV-2 IgG and IgA immunoassay for COVID-19.METHODS:
In this unmatched (12) case-control validation study, we used sera of 181 laboratory-confirmed SARS-CoV-2 cases and 326 controls collected before SARS-CoV-2 emergence. Diagnostic accuracy of the immunoassay was assessed against a whole spike protein-based recombinant immunofluorescence assay (rIFA) by receiver operating characteristic (ROC) analyses. Discrepant cases between ELISA and rIFA were further tested by pseudo-neutralization assay.RESULTS:
COVID-19 patients were more likely to be male and older than controls, and 50.3% were hospitalized. ROC curve analyses indicated that IgG and IgA had high diagnostic accuracies with AUCs of 0.990 (95% Confidence Interval [95%CI] 0.983-0.996) and 0.978 (95%CI 0.967-0.989), respectively. IgG assays outperformed IgA assays (p=0.01). Taking an assessed 15% inter-assay imprecision into account, an optimized IgG ratio cut-off > 2.5 displayed a 100% specificity (95%CI 99-100) and a 100% positive predictive value (95%CI 96-100). A 0.8 cut-off displayed a 94% sensitivity (95%CI 88-97) and a 97% negative predictive value (95%CI 95-99). Substituting the upper threshold for the manufacturer's, improved assay performance, leaving 8.9% of IgG ratios indeterminate between 0.8-2.5.CONCLUSIONS:
The Euroimmun assay displays a nearly optimal diagnostic accuracy using IgG against SARS-CoV-2 in patient samples, with no obvious gains from IgA serology. The optimized cut-offs are fit for rule-in and rule-out purposes, allowing determination of whether individuals in our study population have been exposed to SARS-CoV-2 or not. IgG serology should however not be considered as a surrogate of protection at this stage.Keywords
Full text:
Available
Collection:
International databases
Database:
MEDLINE
Main subject:
Pneumonia, Viral
/
Immunoglobulin A
/
Immunoglobulin G
/
Immunoassay
/
Coronavirus Infections
/
Clinical Laboratory Techniques
/
Betacoronavirus
/
Antibodies, Viral
Type of study:
Diagnostic study
/
Observational study
/
Prognostic study
Limits:
Adult
/
Child
/
Female
/
Humans
/
Male
Language:
English
Journal:
Clin Microbiol Infect
Journal subject:
Communicable Diseases
/
Microbiology
Year:
2020
Document Type:
Article
Affiliation country:
J.cmi.2020.06.024
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