Level of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) immunoglobulin (IgG) antibodies following Covishield vaccination in Bangladesh. Receptor-binding-domain-specific serum IgG antibody responses in participants receiving the Covishield vaccine. Levels of IgG antibodies were analysed using enzyme-linked immunosorbent assay before administration of the first dose of vaccine (Pre V, n=119), and 1 month (day 30±10, n=126), 2 months (day 60±10, n=75), 3 months (day 90±10, n=161), 4 months (day 120±10, n=32), 5 months (day 150±10, n=57) and 6 months (day 180±10, n=47) after the first dose. A second dose was given 2 months after the first dose. Bars indicate geometric mean (GM) concentrations of IgG with 95% confidence intervals (CI). The dashed line indicates the cut-off concentration of IgG antibody (500 ng/mL) for seropositivity. The number and percentage of seropositive individuals at each time point analysed are shown below the graph. *P<0.05, ⁎⁎P<0.01, ⁎⁎⁎P<0.001; ns, not significant.