Is the SARS-CoV-2 Rapid Antigen Detection Test reliable?

07/03/2022
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Rapid antigen detection devices ( RAD ) for SARS-CoV-2 represent a valuable tool for monitoring the spread of infection. However, the reliability of the tests depends largely on the test performance and the respective sampling method.
Nasopharyngeal swabs mark the gold standard for sample collection in suspected respiratory  tract infections but are unsuitable for widespread application, as they must be performed by medically trained personnel. With the study included 87 participants,Participants self-performed one oral and one anterior nasal swab for the rapid antigen test, immediately followed by two nasopharyngeal swabs for the rapid antigen test and RT-PCR by the investigator. The overall sensitivity of rapid antigen detection tests versus that of RT-PCR with oral, anterior nasal, and nasopharyngeal samples was 18.18% (95% confidence interval [CI] 8.19% to 32.71%), 63.04% (95% CI 47.55% to 76.79%), and 73.33% (95% CI 58.06% to 85.4%), respectively. All sampling methods had a test specificity of 100% regardless of the cycle threshold (CT) value.
Rapid antigen detection tests using self-collected anterior nasal swabs proved to be as sensitive as and more tolerable than professionally collected nasopharyngeal swabs for CT values up to 30 determined by RT-PCR. This finding illustrates the reliability of tests obtained by adequate self-collected anterior nasal specimen. Sensitivity was dependent upon the CT value for each sampling method. While the main advantage of rapid antigen detection tests is the immediate availability of results, PCR should be preferred in crucial settings wherever possible.

FIG 1 Sensitivity of RAD tests for CT value categories and cumulated CT values. AN, anterior nasal; NP, nasopharyngeal; RT-PCR, reverse transcriptase PCR.


 

AN, anterior nasal; NP, nasopharyngeal;
TABLE 1 Diagnostic test parameters of RAD devices


AN, anterior nasal; NP, nasopharyngeal; CI, confidence interval; PPV, positive predictive value; NPV, negative predictive value; NA, not applicable

REFERENCE
Michael Wölfl-Duchek,  Felix Bergmann,  Anselm Jorda, Maria Weber,  Matthias Müller,  Tamara Seitz, Alexander Zoufaly, Robert Strassl, Markus Zeitlinger, Harald Herkner, Harald Schnidar, Karolina Anderle, Ulla Derhaschnig. Sensitivity and Specificity of SARS-CoV-2 Rapid Antigen Detection Tests Using Oral, Anterior Nasal, and Nasopharyngeal Swabs: a Diagnostic Accuracy Study Microbiol Spectr. 2022 Jan-Feb; 10(1): e02029-21. PMID: 35107327