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Updated: Oct 1, 2025
Dynamic Monitoring of Seroconversion using a Multianalyte Immunobead Assay for Covid-19
Published on: February 16, 2022
Determining the reliability of rapid SARS-CoV-2 antigen detection in fully vaccinated individuals
Nareshkumar Poopalasingam1, Michael Korenkov1, Artem Ashurov1
1Institute of Virology, Faculty of Medicine and University Hospital Cologne, University of Cologne, Fürst-Pückler-Straße 56, 50935 Cologne, Germany.
Background:
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.
Objectives:
RT-qPCR and rapid antigen detection testing were performed to evaluate the performance of the Standard Q COVID-19 Ag Test in detecting SARS-CoV-2 breakthrough infections in vaccinated individuals.
Study Design:
Two swab specimens, one for RT-qPCR and one for RADT, were collected from vaccinated individuals in an outpatient clinic. For comparison of RADT performance in vaccinated and unvaccinated individuals, a dataset already published by this group was used as reference.
Results:
During the delta wave, 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.
Conclusion:
Our results show that RADT testing remains a valuable tool in detecting breakthrough infections with high viral RNA loads.
