Diagnostic Performance of Three Serological Assays for Anti-SARS-CoV-2 Antibody Detection

Abstract: Objective: To evaluate the diagnostic performance of Electrochemiluminescence (ECLIA) enzyme linked immunosorbent (ELISA) and lateral flow Immunofluorescence (LFIA) for anti-SARS-COV-2 antibody detection. Materials and Methods: Sensitivity was calculated with convalescent plasma (CP) donor’s samples. Specificity was checked by using pre-pandemic October 2019 samples. All samples were tested for anti-SARS-COV-2 antibody by using Electrochemiluminescence (ECLIA), Enzyme Linked Immunosorbent Assay (ELISA) and Lateral flow Immunofluorescence (LFIA) assay. Results: Total 55 patients were included, 45 patients were CP donors and 10 were Pre-Pandemic October 2019 samples archived from our blood bank. The ECLIA-total antibody, ELISA-IgG and LLFIA-IgG were positive in 41 (91.1%), 34 (75.5%) and 44 (97.75%) respectively. The highest sensitivity was observed for LFIA with highest specificity among all three assays. There was almost perfect agreement between LFIA and ECLIA (k=0.936, p<0.001) but there was fair agreement between LFIA and ELISA (k=0.412, p=0.001) and ECLIA and ELISA (k=0.357, p=0.001). Conclusion: The LFIA showed a higher sensitivity and specificity in comparison with ECLIA and ELISA. It might be due to fact that LFIA detect antibody against ncleocapsid and spike protein as well of SARS- COV-2 virus, while ECLIA and ELISA detects antibodies only against “N” Protein of SARS- COV-2 virus. Keywords: Convalescent plasma donors, Lateral flow Immunofluorescence assay, Electrochemiluminescence assay, Enzyme linked immunosorbent assay, Performance.