Fig. 2

Antibody titers at each point after vaccination. HD group had significantly lower anti-S1 antibody titers before the second vaccination (HD: 35.6 BAU/mL vs Control: 99.4 BAU/mL, p < 0.0001), 2 weeks after the second vaccination (HD: 1,085 BAU/mL vs Control: 1,460 BAU/mL, p = 0.0002), and 3 months after the second vaccination (HD: 212.3 BAU/mL vs Control: 232.2 BAU/mL, p = 0.045) than the Control group (a–c). In addition, significant differences were observed 3 weeks after the first vaccination and 2 weeks after the second vaccination for males, and only 3 weeks after the first vaccination for females (a–c). Furthermore, from 2 weeks to 3 months after the second vaccination, the reduction rate of antibody titers (from 2 weeks to 3 months) was significantly smaller in HD group than in Control (HD: 0.819 vs Control: 0.846, p = 0.029), and, according to sex, only significant in male (d). e Time course of anti-S1 antibody titers over 3 months. *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001. 3 W, 3 weeks; 2 W, 2 weeks; 3 M, 3 months; HD, hemodialysis; M, male; F, female; BAU, binding antibody unit