Immunochromatographic Detection of SARS CoV-2 Antigen In Comparison With the Polymerase Chain Reaction for Laboratory Diagnosis of Covid-19 in Karachi, Pakistan

Abstract

Introduction: The Covid-19 pandemic raised the question of which laboratory test was relevant for a rapid and accurate diagnosis of the disease. The current two methods for the detection of SARS CoV-2 are the ICT (Immunochromatographic Technique) and the PCR (Polymerase Chain Reaction) tests; therefore comparative analysis of test performance has to be done.

Objective: To perform a comparative analysis of two different techniques (Immunochromatographic technique for Antigen and Polymerase Chain Reaction for RNA) which are implicated for the detection of SARS CoV-2.

Materials & Methods: The Rapid Antigen Test (RAT) and Polymerase Chain Reaction (PCR) were performed for the detection of Covid-19 on individuals having the signs and symptoms of SARS Covid-19. Immunochromatographic technique (ICT) was performed by SD Biosensor kits, while for Polymerase Chain Reaction RNA extraction was performed by Liferiver® auto extraction analyzer, and amplification was performed by SLAN®-48P Real-Time PCR System.

Results: Among of 100 samples tested, 62 (23.56%) were positive on ICT while PCR had 66 (22.44%) and 38 were negative on ICT while PCR had 34. Thus the sensitivity of ICT was 90.77% (95% CI, 80.98% - 96.54%) and specificity was 91.43% (95% CI 76.94%-98.20%). The Positive Predictive Value was 95.16% while the Negative Predictive Value was 84.21%. However the Cohen’s Kappa Index Value was recorded as 0.806.

Conclusion: The clinical performance of SD Biosensor Roche kits was excellent. On the basis of sensitivity and specificity it was concluded that RAT have comparable results with RT PCR.

Keywords: Antigen, COVID-19, diagnosis, immunoassay, PCR, SARS-CoV-2.