Time scale performance of rapid antigen testing for SARS-COV-2: evaluation of ten rapid antigen assays

ABSTRACT

There is a great demand for more rapid tests for SARS-COV-2 detection to reduce waiting time, boost public health strategies for combating disease, decrease costs, and prevent overwhelming laboratory capacities. This study was conducted to assess the performance of 10 lateral flow device viral antigen immunoassays for the detection of SARS-CoV-2 in nasopharyngeal swab specimens. We analyzed 231 nasopharyngeal samples collected from October 2020-December 2020, from suspected COVID-19 cases and contacts of positive cases at Biotechnology Research Center laboratories, Tripoli, Libya. The performance of 10 COVID-19 Antigen (Ag) rapid test devices for the detection of SARS-CoV-2 antigen was compared to RT-qPCR. In this study 161 cases had symptoms consistent with COVID-19. The mean duration from symptom onset was 6.6 {+/-}4.3 days. The median cycle threshold (Ct) of positive samples was 25. Among the 108 positive samples detected by RT-qPCR, the COVID-19 antigen (Ag) tests detected 83 cases correctly. All rapid Ag test devices used in this study showed 100% specificity. While tests from 6 manufacturers had an overall sensitivity range from 75-100%, the remaining 4 tests had sensitivity of 50-71.43%. Sensitivity during the first 6 days of symptoms and in samples with high viral loads (Ct<25), was 100% in all but 2 of the test platforms. False negative samples had a median Ct of 34 and an average duration of onset of symptoms of 11.3 days (range=5-20 days). Antigen test diagnosis has high sensitivity and specificity in early disease when patients present less than 7 days of symptom onset. Patients are encouraged to test as soon as they get COVID-19 related symptoms within 1 week and to seek medical advice within 24 hrs. if they develop disturbed smell/taste. The use of rapid antigen tests is important for controlling COVID-19 pandemic and reducing burden on molecular diagnostic laboratories.