Rapid antigen test as a screening tool for SARS-CoV-2 infection: Head-to-head comparison with qRT-PCR in Ethiopia

This study aimed to determine the diagnostic accuracy of the antigen rapid diagnostic test (Ag-RDT) as a screening tool for SARS-CoV-2 infection compared to Quantitative reverse transcription polymerase chain reaction (qRT-PCR). Methods: This study was conducted at six referral hospitals in Oromia Region, Ethiopia. One thousand seven hundred twenty-one patients who visited the hospitals for various medical conditions were tested with qRT-PCR and/or Ag-RDTs. Qualitative detection of SARS-CoV-2 antigen was performed using the Panbio™ COVID-19 Ag rapid test device. Results: Compared with qRT-PCR, Ag-RDTs had a sensitivity of 33.3% (95% CI: 30.9%–35.9%) and a specificity of 99.3% (95% CI: 98.8%–99.7%) to detect active SARS-CoV-2 infection. The area under the receiver operator curve was 0.67 (95% CI: 0.63–0.69). The sensitivity of Ag-RDTs appeared high in patients with shortness of breath (73.3%) and those presenting with all three symptoms—fever, cough, and dyspnea (71.4%). In all instances, specificity was more than 98%. The Ag-RDT positivity rate also correlated well with viral load: 51.7% in cases with cycle threshold (Ct) < 25 (high viral load) and only 3.4% when Ct > 25 (low viral load). Conclusion: Although Ag-RDT for diagnosing SARS-CoV-2 is a good option as a point-of-care screening tool, it has a low sensitivity to detect active infections. Using Panbio™ COVID-19 Ag Rapid test for diagnostic and treatment decisions may lead to a false negative, resulting in patient misdiagnosis, ultimately contributing to disease spread and poor patient outcome.