Covishield-induced antibody responses in different gender and age groups. Receptor-binding-domain-specific serum immunoglobulin G (IgG) antibody responses in (A) male and female participants before the first dose of vaccine (Pre V, n=81 male, n=38 female), and 1 month (n=80 male, n=46 female), 2 months (n=48 male, n=27 female), 3 months (n=98 male and n=63 female), 4 months (n=26 male, n=6 female), 5 months (n=37 male, n=20 female) and 6 months (n=26 male, n=21 female) after the first dose. (B) Vaccine-induced IgG antibodies in participants aged <40 years vs ≥40 years before the first dose (n=56 vs 63), and 1 month (n=42 vs 84), 2 months (n=21 vs 54), 3 months (n=39 vs 122), 4 months (n=15 vs 17), 5 months (n=16 vs 41) and 6 months (n=16 vs 31) after the first dose. A second dose was given 2 months after the first dose. Each symbol indicates data from one participant, and bars represent geometric mean (GM) concentrations of IgG. The dashed line indicates the cut-off concentration of IgG antibody (500 ng/mL) for seropositivity. Number and percentage of seropositive individuals in each time points analysed are shown below the graph. *P<0.05, ⁎⁎P<0.01, ⁎⁎⁎P<0.001. ns, not significant.