Immune response and safety of the adjuvanted recombinant zoster vaccine in adults 50 years of age and older in India: A randomized phase 3 trial.

BACKGROUND

Reactivation of latent varicella-zoster virus can cause herpes zoster (shingles) and associated complications, such as post-herpetic neuralgia. The adjuvanted recombinant zoster vaccine (RZV) was shown to be efficacious in preventing herpes zoster and have an acceptable safety profile in adults ≥50 years of age. However, no clinical data on RZV were available in an Indian population. The aim of the current study was to assess the immunogenicity and safety of RZV in adults ≥50 years of age in India.

METHODS

In this randomized, placebo-controlled, observer-blind, multi-center trial, conducted between February 2022 and March 2023, participants ≥50 years of age received two doses (with a two-month interval) of RZV (N = 143) or placebo (N = 145). Blood samples were collected pre-dose 1 and one month post-dose 2 to quantify anti-glycoprotein E (gE) antibody concentrations. Solicited adverse events (AEs) with onset within seven days and unsolicited AEs with onset within 30 days following any RZV or placebo dose were recorded. Serious AEs (SAEs) and potential immune-mediated diseases (pIMDs) were recorded until trial end (six months post-dose 2).

RESULTS

At one month post-dose 2, vaccine response rate in the RZV group was 85.7 % (95 % confidence interval [CI]: 78.4 %-91.3 %), meeting the primary objective's success criterion (lower limit of 95 % CI ≥60 %). The adjusted geometric mean anti-gE antibody concentration ratio between the RZV and placebo groups was 19.8 (95 % CI, 14.1-27.8), meeting the secondary objective's success criterion (lower limit of 95 % CI ≥3). Solicited AEs were reported by 103 (72.0 %) RZV and 86 (59.3 %) placebo recipients; most had mild-to-moderate severity. No intervention-related unsolicited AE or SAE and no pIMD or death were reported.

CONCLUSION

Two doses of RZV induced a robust antibody response, comparable to that reported in other populations, and had a safety profile similar to the known RZV safety profile.

CLINICALTRIALS: gov: NCT05219253.