LAUSR

Abstract Background The 2-dose recombinant zoster vaccine (RZV) series is recommended for prevention of herpes zoster (HZ) in adults aged ≥50 years, but data are limited on the impact of concomitant administration with other vaccines on subsequent HZ risk. Methods This cohort study included Kaiser Permanente Southern California members aged ≥50 years who received 2 doses of RZV 4 weeks to ≤6 months apart during 1 April 2018–30 September 2019. RZV recipients with and without same-day concomitant vaccination for either RZV dose were followed up for incident HZ beginning 31 days after the second RZV dose until 30 September 2020. The hazard ratio (HR) for HZ comparing RZV recipients with and without concomitant vaccination was estimated using Cox proportional hazards regression, adjusting for confounders. Results RZV with and without concomitant vaccination was received by 12 898 and 28 353 individuals, respectively. HZ occurred among 41 individuals with concomitant vaccination (incidence rate, 2.2 [95% confidence interval {CI}, 1.6–3.0] per 1000 person-years) and 136 without concomitant vaccination (3.4 [95% CI, 2.9–4.0] per 1000 person-years). The adjusted HR for HZ comparing RZV recipients with and without concomitant vaccination was 0.75 (95% CI, .53–1.08). Conclusions HZ risk was not significantly different between RZV recipients with and without concomitant vaccination, supporting recommendations allowing for concomitant administration of RZV with other vaccines.