Impact of CD4 T Cell Counts on the Immunogenicity and Safety of the Recombinant Zoster Vaccine in People Living with HIV.

OBJECTIVES: People living with HIV (PLWH) are at increased risk for herpes zoster. This study aimed to evaluate and compare the immunogenicity and safety of the recombinant zoster vaccine (RZV) in PLWH across low and high CD4 counts, and in participants living without HIV (PLWoH). METHODS: In this non-randomized clinical trial, virologically suppressed PLWH receiving antiretroviral therapy and PLWoH received two doses of RZV. PLWH were stratified into low (<300 cells/μL) and high (≥300 cells/μL) CD4 groups. Anti-glycoprotein E (gE) antibody titers and gE-specific cell-mediated immunogenicity (CMI) were measured at baseline, 8 weeks post-dose one, and 4 weeks post-dose two. Vaccine response rates (VRRs), defined as a ≥4-fold antibody or ≥2-fold CMI increase, and reactogenicity were assessed. RESULTS: Sixty PLWH (30 low CD4, 30 high CD4) and 10 PLWoH (all male) were analyzed. Anti-gE titers increased significantly after each dose with no between-group differences. All groups achieved 100% humoral VRR after dose two, whereas CMI VRR differed significantly (33.3% low CD4, 50.0% high CD4, 80.0% PLWoH; P=0.041). Reactogenicity profiles were comparable. CONCLUSION: RZV elicited robust humoral immunity in PLWH, regardless of the CD4 count; however, CMI was lower in PLWH than in HIV-negative individuals.