Rapid antigen detection kit for the diagnosis of SARS-CoV-2 - are we missing asymptomatic patients?

Abstract

Purpose To determine the utility, diagnostic accuracy, sensitivity, specificity, and negative predictive value of the laboratory based Covid-19 antigen detection test (Coris Bio- Concept, Gembloux, Belgium) for the diagnosis of SARS-CoV-2 in a tertiary care hospital among symptomatic and asymptomatic patients. Methods The nasopharyngeal swab samples were collected from the symptomatic patients and their contacts. The diagnostic accuracy of this antigen kit was determined in comparison to SARS-CoV-2 real-time reverse transcriptase (RT-PCR). Results A total of 825 patients fulfilling the inclusion criteria were included in the study; RT-PCR and antigen detection was performed simultaneously for 484 samples to determine the sensitivity and specificity of the test. The overall specificity and sensitivity was 99.32% and 71.96% respectively. Also, 3.7% of the asymptomatic patients who were negative by RAT were detected positive by RT-PCR. Conclusion This rapid antigen test (RAT) was sensitive in the symptomatic patients presenting during the initial phase of the illness. Since, majority of the SARS-CoV-2 patients are asymptomatic and considering the huge population, the testing strategy formulated by Indian Council of Medical Research (ICMR) at the national level was cost effective. Thus, Ag-RDTs could play a pivotal role in early diagnosis, policy making and surveillance of the SARS-CoV-2.

Update on Rapid Diagnostics for COVID-19: A Systematic Review

“…Lower sensitivity was also observed in samples that showed high Ct values in RT-PCR [17][18][19]24,[26][27][28][30][31][32][33][34]36,38,39,42,43,47,53], indicating a lower viral load. In SARS-CoV-2 infection, the viral load peaks in the first week after the onset of symptoms in the upper respiratory tract.…”

“…Suboptimal sensitivity was also observed in samples with low viral loads (high Ct value in RT-PCR) [17][18][19]24,[26][27][28][30][31][32][33][34]36,38,39,42] and in pediatric samples, when compared with samples from adult patients [22,24,25,28]. Only two studies showed values of specificity lower than 98% (64.2% and 83.3%) [36,42].…”

“…In the studies reporting direct detection, 37 reported the sensitivity and specificity of the test [47][48][49][50][51][53][54][55], 11 studies provided information about diagnostic accuracy [22,23,26,27,31,32,34,[36][37][38]54], and 2 studies did not reveal any of these parameters, mentioning only the limit of detection [46,52] (Table 1). All studies that reported sensitivity used RT-PCR variations as reference standards to determine SARS-CoV-2 infection.…”

“…Diagnostic accuracy was reported in only 11 studies [22,23,26,27,31,32,34,[36][37][38]55], with values greater than 80% except for one study that reported 75.9% [36], demonstrating that the developed tests had a good performance in detecting SARS-CoV-2. Otherwise, cross-reaction analyses were verified in only nine studies, showing the need to improve the diagnostic performance and the information provided about them.…”

Can Self-Administered Rapid Antigen Tests (RATs) Help Rural India? An Evaluation of the CoviSelf Kit as a Response to the 2019–2022 COVID-19 Pandemic

“…The Cochrane Report confirmed the value of all the above factors when using RATs for widespread diagnostic purposes [23]. Another study spoke of the benefits of RATs involving 'triage and emergencies' needing priority diagnoses [24]. RATs have long been used for diagnosing other illnesses, such as pharyngitis caused by Streptococcus bacteria [25] and Bancroftian filariasis [26].…”