Determining the Reliability of Rapid SARS-CoV-2 Antigen Detection in Fully Vaccinated Individuals
23 Pages Posted: 4 Jan 2022
Abstract
Rapid antigen detection tests (RADT) are commonly used as SARS-CoV-2 diagnostic tests both by medical professionals and laypeople. However, the performance of RADT in vaccinated individuals has not been fully investigated. Here, RT-qPCR and rapid antigen detection testing were performed in an outpatient clinic to evaluate the performance of the Standard Q COVID-19 Ag Test in detecting SARS-CoV-2 breakthrough infections in vaccinated individuals. A total of 696 samples were tested with both RT-qPCR and RADT that included 692 (99.4%) samples from vaccinated individuals. Of these, 76 (11.0%) samples were detected SARS-CoV-2 positive by RT-qPCR and 45 (6.5%) samples by the Standard Q COVID-19 Ag test. Stratified by Ct values, sensitivity of the RADT was 100.0%, 94.4% and 81.1% for Ct ≤ 20 (n=18), Ct ≤ 25 (n=36) and Ct ≤ 30 (n=53), respectively. Samples with Ct values ≥ 30 (n=23) were not detected. Overall RADT specificity was 99.7% and symptom status did not affect RADT performance. Notably, RADT detected 4 out of 4 samples of probable Omicron variant infection based on single nucleotide polymorphism analysis. Our results show that RADT testing remains a valuable tool in detecting breakthrough infections with high RNA loads.
Note:
Funding: Bundesministerium für Bildung und Forschung grant 01KX2021 („B- FAST“, „NaFoUniMedCovid19“)
Declaration of Interests: The authors declare no competing interests.
Ethics Approval Statement: The Institutional Review Board of the University of Cologne acknowledged and approved the study under application number 21-1039.
Keywords: SARS-CoV-2, antigen test, RT-qPCR, vaccination, Omicron
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