SARS-CoV-2 IgG Antibody and its Clinical Correlates in Convalescent Plasma Donors: An Indian Experience

SARS-CoV-2, a novel coronavirus, emerged a year ago in Wuhan, China causing a new pandemic. Convalescent plasma therapy has been applied previously to many infectious diseases and has shown a successful result. This study was planned to assess the Anti-SARS-CoV-2 IgG antibody levels in convalescent COVID-19 patients. In this study, serum samples from 210 persons infected by SARS-CoV-2, treated and discharged from the hospital were collected. Anti-SARS-CoV-2 IgG antibody levels were detected using a chemiluminescence assay. A directory of convalescent plasma donors was created. Anti-SARS-CoV-2 IgG antibody levels vary substantially in the study population with a mean of 51.2 AU/ml. On comparing the serum anti-SARS-CoV-2 IgG antibody levels, a significant difference was observed between the subjects who had cough and those who did not (p = 0.0004). Similar significant findings were found with total protein and globulin levels on comparing the individuals with different antibody status (positive, negative and equivocal). The middle-aged and old age people had high Ab titres compared to younger individuals and the duration of the hospital stay was found to be positively correlated with the anti-SARS-CoV-2 IgG antibody. Cough, age and duration of the hospital stay was found to play a significant role in the development of Anti-SARS-CoV-2 IgG levels. Further, the data suggests that blood groups have a lesser impact on the severity of disease and the development of antibodies. Patients who present with the cough are more likely to develop antibodies.