Effectiveness of the Recombinant Zoster Vaccine Among Kaiser Permanente Hawaii Enrollees Aged 50 and Older: A Retrospective Cohort Study

Background: The incidence of herpes zoster (HZ) has been on the rise for decades in the United States. Clinical trials for the recombinant zoster vaccine (RZV) demonstrated vaccine efficacy of over 90% in preventing herpes zoster. However, there is limited information on its effectiveness outside of a clinical trial setting, as well as its effectiveness against herpes zoster ophthalmicus (HZO).

Methods: A de-identified electronic health records database from Kaiser Permanente Hawaii (KPH) was used to conduct this retrospective cohort study to assess the effectiveness of the recombinant zoster vaccine against HZ and HZO in immunocompetent, vaccine age-eligible individuals without a prior history of HZ, who were continuously enrolled in KPH for ≥365 days prior to becoming age-eligible for RZV between January 1, 2018, through December 31, 2019.

Results: A total of 78 356 adults were included in this study, with 11 864 (15.1%) adults receiving two valid doses of the recombinant zoster vaccine. The incidence rate of HZ was 325.6 (95% CI: 217.7 to 464.4) cases per 100 000 person-years in vaccinated persons compared to 1063.3 cases per 100 000 person-years (95% CI: 1006.0 to 1122.8) in the unvaccinated group. The incidence rate of HZO was 11.9 (95% CI: 0.7 to 52.3) cases per 100 000 person-years in the vaccinated group compared to 72.1 (95% CI: 58.0 to 88.3) in the unvaccinated group. RZV was 83.5% (95% CI: 74.9% to 89.2%) effective against HZ and 93.3% (95% CI: 48.7% to 99.1%) effective against HZO.

Conclusions: RZV has demonstrated high effectiveness against both HZ and HZO outside of a clinical trial setting in the United States. Vaccine coverage is low, emphasizing the need for public health efforts to increase vaccination to reduce morbidity from HZ and HZO.