Evaluation of the Performance of the COVID-19 Rapid Antigen Tests in a Tertiary Level Hospital in Bangladesh

The tests providing high sensitivity and specificity are essential to identify and manage COVID-19 patients.There is aheavy demand for low-cost rapid antigen tests (RATs) for COVID-19 with a decent diagnostic value. Globally,several RATs for COVID-19 have been developed, but their clinical efficacy has not been well recognized.Thepurpose of the study was to evaluate the performance of RATs. We conducted this prospective observational study atShaheed Suhrawardy Medical College hospital from February 2021 to April 2021 in Dhaka, Bangladesh. This studyincluded the patients admitted in this hospital at the COVID-19 isolation unit or referred from the triage facility of theoutdoor department of this hospital suspected as COVID-19 case. Two nasopharyngeal samples were collectedsimultaneously. We used one sample on the spot for the RATs and the other was sent to the adjacent ShaheedSuhrawardy Medical College COVID-19 RT-PCR laboratory for real-time reverse transcription PCR (RT-PCR). Theperformance of the RATs was evaluated by consuming the real-time RT-PCR results as a reference. In thisinvestigation, SARS-CoV-2 was identified in 84 (30.7%) of the 223 patients who participated. Of these 84 patients, 9(10.7%) were asymptomatic. The overall sensitivity and specificity of RATs were 78.6% and 99.3%, respectively. Thesensitivity was 81.3% in symptomatic cases and 55.6% in asymptomatic cases. There were 18 false-negativespatients,including 3 asymptomatic cases, who had a low viral load (cycle threshold(Ct) > 30). When the Ct value was up to24, the detection rate of RATs was 100%. The detection rate was 42.3% when the Ct was >29. When symptoms beganwithin three days, the detection rate was 92.3%. When the start of symptoms was over 7 days, the detection rate was33.3%. RATs for COVID-19 used in this study delivered an acceptable performance in patients with high viral loadand within the first week of the onset of symptoms. This method can be a supplementary method to RT- PCR for thediagnosis of symptomatic COVID-19 patients. Bangabandhu Sheikh Mujib Med. Coll. J. 2022;1(2):58-64