Development and evaluation of various SARS-CoV-2 detection tests in Nasopharyngeal specimens in Uganda

Abstract

Background: Although the WHO recommends RT-PCR as reference standard method for detection of SARS-CoV-2 nucleic acid when diagnosing COVID-19 and tracing of contacts, this test is costly, primarily designated for specialised reference laboratories, requires special training of laboratory staff, has long turnaround time for test results and further complicated by the global procurement challenges making it inaccessible for most laboratories in resource limited settings like Uganda. COVID-19 Ag RDTs that meet the minimum performance requirements of ≥ 80% sensitivity and ≥ 97% specificity compared to RT-PCR reference standard were approved for use by WHO in settings where RT-PCR is inaccessible. However, there is inadequate information on the technical performance of Cortez COVID-19 and Abbot PanBio COVID-19 Ag RDTs in the detection of SARS-CoV-2 in nasopharyngeal specimens in Uganda. Objective: The primary objective was to evaluate the technical performance of various SARS-CoV-2 Antigen RDTs against the RT-PCR reference standard for the detection of SARS-CoV-2 in nasopharyngeal swabs. Study Population: Nasopharyngeal samples were obtained from both asymptomatic and symptomatic individuals seeking a COVID-19 PCR test for various reasons. Study site: The study was conducted at MBN Clinical Laboratories in Uganda Methods: Detection of SARS-CoV-2 was performed in parallel using Cortez COVID-19 and Abbott PanBio COVID-19 Ag RDTs and results read at exactly fifteen minutes. Results: The sensitivity, specificity and kappa agreement of Cortez COVID-19 Ag RDT was 36.7% (95% CI 19.9-56.1), 100% (95% CI 98.2-100) and 0.5 respectively. Corresponding values for Abbott PanBio COVID-19 were 6.7% (95% CI 0.8-22.1), 99.5% (95% CI 97.4-100) and 0.1 kappa agreement. Conclusion: The Cortez COVID-19 and Abbott PanBio COVID-19 Ag RDTs used in this study showed a very low sensitivity but very high specificity against the RT-PCR as reference standard method.