Respiratory syncytial virus vaccination induces delayed but robust humoral and cellular immunity in patients receiving hemodialysis

Introduction Respiratory syncytial virus (RSV) causes substantial morbidity in older adults. Patients receiving hemodialysis are particularly vulnerable due to impaired immunity and chronic healthcare exposure. Data on RSV vaccine immunogenicity in this population are lacking. Methods We conducted an observational study of 20 patients receiving hemodialysis (median age 78.4 years; 55% female; median dialysis duration 23 months) who received a single dose of the RSV vaccine Arexvy. Blood samples were obtained at baseline and at weeks two, five, eight, 16, and 32. RSV-specific IgG was quantified by ELISA, and cellular responses were assessed by multiparameter flow cytometry. Fifteen sex- and age-matched individuals with normal kidney function were included as a control group. Results At baseline, 14 of 20 patients were seropositive (IgG over 11 Standard Units (SU); median 12.6 SU). IgG titters remained stable through week five, rose significantly at week eight (16.8 SU), peaked at week 16 (17.5 SU), and declined to 14.6 SU at week 32, remaining above baseline. In contrast, healthy control individuals, vaccinated with Arexvv, showed increasing RSV-IgG antibody levels already after two weeks. Antibody levels correlated negatively with dialysis duration, and patients with under one year of dialysis had significantly higher titers. RSV-specific CD4 + T cells increased at week two, with most producing IFN-γ, IL-2, or TNF, and returned to baseline by week eight. B cell responses included expansion of plasmablasts (weeks five-eight) and early increases in switched memory B cells. Cytokine profiling showed modest changes (IL-23, TNF and IL12p70 increased; IL-8 decreased) Conclusions Arexvy elicited robust humoral and cellular responses in patients receiving hemodialysis. Attenuated antibody responses with longer dialysis duration suggest dialysis vintage as a key determinant of vaccine efficacy in this high-risk population. The increase in anti-RSV IgG antibody levels was significantly delayed in patients receiving hemodialysis compared to control individuals.