Performance evaluation of vitros® anti-sars cov-2 antibody assays (total & igg): an adjunctive screening tool for rtqpcr in covid–19 infection detection

Background: Currently world is facing a pandemic caused by novel corona virus (SARS –CoV2) which causes a highly contagious infection affecting most commonly lungs and results in an array of clinical symptoms ranging from asymptomatic state to acute respiratory distress syndrome and may even lead to multi organ dysfunction.The diagnostic modalities include Reverse transcriptase real time PCR (RTqPCR) which is gold standard method for diagnosis of the infection using oro-pharyngeal or nasopharyngeal swabs from the patients. Aim and Objectives: Evaluation of the performance of VITROS® Anti SARS CoV-2 antibody Assays (Total &IgG) in RT-PCR positive symptomatic COVID -19 patients.A correlation of time gap between RTqPCR/CB-NAT tests and positive serology test will be done for Total antibody. Materials and Method: Blood samples of COVID 19 confirmed patients (by RTqPCR) were tested for Anti SARS CoV2 Total (IgM, IgG&IgA) (ASCV2T). All these ASCV2T positive samples were further tested for Anti SARS CoV2 IgG (ASCV2G) antibodies using VITROS® 3600 immunodiagnostics system as per the manufacturer protocol. Results: A total of 67 patient samples were collected in the period of 02 months from June 2020 & July 2020. Out of these 67 patients 34 were positive and 33 were negative for COVID-19 infection by RTqPCR method. 28 of the 34 RTqPCR positive samples were reactive for total antibody test. As per statistical analysis, ASCV2T assay showed sensitivity 82.35%, specificity 100%, PPV 100%& NPV 84.62%. Conclusion: Serological assay show fair sensitivity (82.35%) & specificity (100%). Both RTqPCR& serological assay as a combination can be used as an important screening tool for COVID 19 infection. This can be further validated by Randomized controlled trails or meta-analysis with large number of sample size for longer duration follow-up.