OBJECTIVES: In an interim analysis, we evaluated vaccine effectiveness (VE) against herpes zoster (HZ) and postherpetic neuralgia (PHN) and safety of recombinant zoster vaccine (RZV) in adults aged ≥50 years with rheumatoid arthritis (RA). METHODS: VE was assessed using a retrospective matched cohort analysis of Kaiser Permanente Southern California members aged ≥50 years with RA receiving 2 RZV doses (≥4 weeks apart) and matched up to 1:3 to RZV-unvaccinated individuals. Stratified Cox proportional hazards regression was used to estimate adjusted hazard ratios and VE against HZ and PHN. Safety was assessed using a self-controlled case series analysis of chart-confirmed RA flare within 30 days after any RZV vaccination versus comparison periods. The relative risk (RR) was estimated using conditional Poisson regression. RESULTS: In adults ≥50 years with RA (2-dose vaccinated: 1926
unvaccinated: 5746), the adjusted VE of 2 RZV doses against HZ was 60.7% (95% CI, 41.0%-73.8%)
in a subgroup analysis among those who received 2 doses 4 weeks to 6 months apart, VE against HZ was 57.9% (95% CI, 34.4%-73.0%). Adjusted VE of 2 RZV doses against PHN was 88.7% (95% CI, 12.1%-98.5%). Among 2606 adults with RA who received ≥1 RZV dose, no increased risk of RA flares within 30 days after RZV vaccination was observed (RR, 1.02
95% CI, 0.75-1.37). CONCLUSIONS: Among adults ≥50 years with RA, 2 RZV doses provided protection against HZ and PHN. The study did not observe an increased risk of RA flares within 30 days following RZV vaccination.