Covid-19 antigen testing: better than we know? A test accuracy study
- 14 May 2021
- journal article
- research article
- Published by Taylor & Francis Ltd in Infectious Diseases
- Vol. 53 (9), 661-668
- https://doi.org/10.1080/23744235.2021.1914857
Abstract
Antigen testing for SARS-CoV-2 is considered to be less sensitive than the standard reference method – real-time PCR (RT-PCR). It has been suggested that many patients with positive RT-PCR ‘missed’ by antigen testing might be non-infectious. In a real-world high-throughput setting for asymptomatic or mildly symptomatic patients, 494 patients were tested using RT-PCR as well as a single lateral flow antigen test (Ecotest, AssureTech, China). Where the results differed, virus viability was evaluated by cell culture. The test parameters were calculated with RT-PCR and RT-PCR adjusted on viability as reference standards. The overall sensitivity of the used antigen test related to the RT-PCR only was 76.2%, specificity was 97.3%. However, 36 out of 39 patients ‘missed’ by the antigen test contained no viable virus. After adjusting on that, the sensitivity grew to 97.7% and, more importantly for disease control purposes, the negative predictive value reached 99.2%. We propose that viability testing should be always performed when evaluating a new antigen test. A well-chosen and validated antigen test provides excellent results in identifying patients who are shedding viable virus (although some caveats still remain) in the real-world high-throughput setting of asymptomatic or mildly symptomatic individuals.Keywords
Funding Information
- Hospital Karvina-Raj
- Public Health Institute Ostrava
This publication has 15 references indexed in Scilit:
- Clinical Evaluation of BD Veritor SARS-CoV-2 Point-of-Care Test Performance Compared to PCR-Based Testing and versus the Sofia 2 SARS Antigen Point-of-Care TestJournal of Clinical Microbiology, 2020
- Author Correction: Virological assessment of hospitalized patients with COVID-2019Nature, 2020
- Evaluation of a novel antigen-based rapid detection test for the diagnosis of SARS-CoV-2 in respiratory samplesInternational Journal of Infectious Diseases, 2020
- Rapid, point-of-care antigen and molecular-based tests for diagnosis of SARS-CoV-2 infectionEmergencias, 2020
- Evaluation of rapid antigen test for detection of SARS-CoV-2 virusJournal of Clinical Virology, 2020
- Predicting Infectious Severe Acute Respiratory Syndrome Coronavirus 2 From Diagnostic SamplesClinical Infectious Diseases, 2020
- Respiratory disease in rhesus macaques inoculated with SARS-CoV-2Nature, 2020
- Development and Potential Usefulness of the COVID-19 Ag Respi-Strip Diagnostic Assay in a Pandemic ContextFrontiers in Medicine, 2020
- Temporal dynamics in viral shedding and transmissibility of COVID-19Nature Medicine, 2020
- Virological assessment of hospitalized patients with COVID-2019Nature, 2020