Real-world accuracy of SARS-CoV-2 antigen detection compared with qPCR: A cross-sectional study in Toledo - PR, Brazil

Real-world accuracy of SARS-CoV-2 antigen detection compared with qPCR: A cross-sectional study in Toledo - PR, Brazil

Rapid Antigen Tests (Ag-RDTs) for the detection of SARS-CoV-2 is an important diagnostic tool for containing virus spread. However, their accuracy ‒ the proportion of correct results (both true positives and true negatives) ‒ still needs to be proven when used in a real large-scale context. Accordin...

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Main Authors: Carla Adriane Royer, Regis Goulart Rosa, Maicon Falavigna, Jaqueline Carvalho de Oliveira, Mariana Motta Dias da Silva, Carolina Gracia Poitevin, Hellen Abreu, Valter Antonio Baura, Ana Claudia Bonatto, Daniela Fiori Gradia, Cristina de Oliveira Rodrigues, Rafael Messias Luiz, Ana Paula Carneiro Brandalize, Josélia Larger Manfio, Cintia Laura Pereira de Araujo, Ana Paula de Souza, Daniel Sganzerla, Caroline Cabral Robinson, Fernanda Kelly Romeiro Silva, Gabriela Almeida Kucharski, Fernando Pedrotti, Srinivas Rao Valluri, Amit Srivastava, Viviane Wal Julião, Olga Chameh Melone, Florence Lefebvre d'Hellencourt, Moe H Kyaw, Julia Spinardi, Graciela del Carmen Morales Castillo, Emanuel Maltempi de Souza
Format: Article
Language:English
Published: Elsevier 2025-05-01
Series:Brazilian Journal of Infectious Diseases
Subjects:
COVID-19
Performance
Rapid antigen tests
Viral load
Online Access:http://www.sciencedirect.com/science/article/pii/S1413867025000236
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Summary:Rapid Antigen Tests (Ag-RDTs) for the detection of SARS-CoV-2 is an important diagnostic tool for containing virus spread. However, their accuracy ‒ the proportion of correct results (both true positives and true negatives) ‒ still needs to be proven when used in a real large-scale context. Accordingly, we provide data from a cross-sectional study conducted in Toledo - PR, Brazil, on the accuracy of rapid tests compared with qPCR within the Brazilian Unified Health System. A total of 2882 thousand individuals presenting symptoms suggestive of COVID-19 were screened. Overall, the antigen tests showed a sensitivity, specificity, and accuracy of 59 % (0.56‒0.62), 99 % (0.98‒0.99), and 82 % (0.81‒0.84) respectively. However, a significant difference was found when analysing two brand tests individually. In addition, for patients with a low quantification Cycle (Cq) < 20 (which indicates a high viral load), the agreement between test results was high (90.85 %). However, this agreement decreased significantly when the viral load decreased, dropping to 5.59 % for samples with Cq ≥ 33, which indicates a lower viral load. While rapid antigen tests are a valuable tool in combating virus spread, their accuracy can vary significantly between manufacturers and under conditions of low viral load.
ISSN:1413-8670

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