Comparison of the Diagnostic Performance of a Rapid Antigen Test with Real-Time Polymerase Chain Reaction for Detection of SARS-CoV-2 Among Patients Diagnosed with COVID-19 at Selected Hospitals in Addis Ababa, Ethiopia.

ABSTRACT

Background: When faced with a public health problem such as the COVID-19 pandemic, devising a test with an accurate and rapid diagnostic capacity is critical to contain the disease. We compared the diagnostic performance of a rapid antigen test in comparison with a reference method, namely a real-time polymerase chain reaction (RT-PCR) assay. Methods: We enrolled patients with confirmed COVID-19 from two selected hospital in Addis Ababa, Ethiopia, between January and November 2021. We assessed the performance of the Standard Q COVID-19 Ag Kit (SD Biosensor, Republic of Korea) in 200 nasopharyngeal and nasal swab samples. Results: Out of the 200 samples utilized for the diagnostic performance evaluation, equal proportion of the samples were confirmed positive and negative for SARS-CoV-2 based on RT-PCR. Of the 100 confirmed positive cases, 95 showed positive results with the rapid antigen test, yielding a sensitivity of 95% (95% confidence interval [CI] 88.7-98.4%). Of the 100 confirmed negative cases, there were three false-positive results, yielding a specificity of 97% (95% CI 91.5-99.4%). The sensitivity of the rapid antigen test was higher for samples with an RT-PCR cycle threshold (Ct) value ≤25 compared with samples with a higher Ct value. Conclusion: The finding demonstrated that the detection capacity of the Standard Q COVID-19 Ag Test meets the requirements set by the Ministry of Health Ethiopia. The high sensitivity and specificity of the test device indicate the possibility of using it for diagnostic and clinical purposes in resource-constrained settings such as Ethiopia.