Comparison of Antigen Tests and qPCR in Rapid Diagnostics of Infections Caused by SARS-CoV-2 Virus

Abstract

Diagnostics of the coronavirus disease 2019 (COVID-19) using molecular techniques from the collected respiratory swab specimens requires well-equipped laboratory and qualified personnel, also it needs several hours of waiting for results and is expensive. Antigen tests appear to be faster and cheaper but their sensitivity and specificity are debatable. The aim of this study was to compare a selected antigen test with quantitative polymerase chain reaction (qPCR) tests results. Nasopharyngeal swabs were collected from 192 patients with COVID-19 symptoms. All samples were tested using Vitassay qPCR SARS-CoV-2 kit and the Humasis COVID-19 Ag Test (MedSun) antigen immunochromatographic test simultaneously. Ultimately, 189 samples were tested; 3 samples were excluded due to errors in taking swabs. The qPCR and antigen test results were as follows: 47 positive and 142 negative, and 45 positive and 144 negative, respectively. Calculated sensitivity of 91.5% and specificity of 98.6% for the antigen test shows differences which are not statistically significant in comparison to qPCR. Our study showed that effectiveness of the antigen tests in rapid laboratory diagnostics is high enough to be an alternative and support for nucleic acid amplification tests (NAAT) in the virus replication phase in the course of COVID-19.

Extraction-Free Detection of SARS-CoV-2 Viral RNA Using LumiraDx’s RNA Star Complete Assay from Clinical Nasal Swabs Stored in a Novel Collection and Transport Medium

“…For example, a high value, e.g., C T = 36, indicates a low concentration of vRNA targets in the sample (Note: a C T value of 45 = no detectable vRNA targets, according to CDC’s RT-qPCR assay). Thus, in an RT-qPCR analysis, a low copy concentration, when a CT value is high, may be reported as “positive” for SARS-CoV-2 despite being negative in other tests such as rapid antigen tests [ 23 , 24 , 25 ]. The three patients that were missed via the RSC testing but found to be positive via the CDC’s test were from low-target samples in which the C T values were >34.8.…”

Field evaluation of COVID-19 rapid antigen test: Are rapid antigen tests less reliable among the elderly?

“…There are only a few studies that evaluated Humasis Covid-19 RAT. Klajmon et al [ 8 ] tested 189 samples using RT-PCR and RAT simultaneously. The calculated negative predictive value (97.22%) was higher than our study but more similar to Abbot's PanBio RAT (94.6% and 99.5%, respectively).…”

“…Identifying and confirming COVID-19 in symptomatic persons is important to provide appropriate care and implement public health measures without delay[ 11 ]. Therefore, despite the limitations of RAT, including inferior results to RT-PCR[ 8 , 12 ], their previously described use is effective and can be a support for RT-PCR testing of SARS-CoV-2. Nevertheless, the RAT cost is significantly lower than RT-PCR[ 13 ].…”

Update of European Society of Clinical Microbiology and Infectious Diseases coronavirus disease 2019 guidelines: diagnostic testing for severe acute respiratory syndrome coronavirus 2

“… In patients with signs and symptoms compatible with COVID-19, we suggest the use of laboratory based NAAT in nasopharyngeal samples versus rapid antigen detection testing in nasopharyngeal samples for the diagnosis of COVID-19. Weak against Very low [ 4 , 5 , 16 , 106 , [17] , [18] , [19] , [20] , [21] , [22] , [23] , [24] , [25] , 6 , [26] , [27] , [28] , [29] , [30] , [31] , [32] , [33] , [34] , [35] , 8 , [36] , [37] , [38] , [39] , [40] , [41] , [42] , [43] , [44] , [45] , 10 , [46] , [47] , [48] , [49] , [50] , [51] , [52] , [53] , [54] , [55] , 11 , [56] , [57] , [58] , [59] , [60] , [61] , [62] , [63] ...…”

“…[ 27 ]; [ 30 ]; [ 32 ]; [ 42 ]; [ 51 ]; [ 52 ]; [ 58 ]; [ 59 ]; [ 69 ]; [ 72 ]; [ 74 ]; [ 80 ]; [ 84 ]; [ 88 ]; [ 98 ]; [ 103 ]; [ 134 ]; [ 144 ]; [ 145 ]; [ 150 ]; [ 153 ]; [ 157 ]; [ 162 ]; [ 169 ]; [ 173 ]; [ 174 ]; [ 178 ]; [ 179 ]; [ 180 ]; [ 181 ]; [ 182 ].…”