In 2009, a revision to the zoster vaccine package insert was approved stating that the zoster vaccine and the pneumococcal vaccine should not be given concurrently because concomitant use resulted in reduced immunogenicity of the zoster vaccine. We conducted an observational study to evaluate if concomitant vaccination reduces the protective effect of the zoster vaccine. The study was conducted in Kaiser Permanente Southern California. Incidence of herpes zoster (HZ) after vaccination with a zoster vaccine in the population receiving both vaccines on the same day was compared to that in the population receiving a pneumococcal vaccine within one year to 30 days prior to zoster vaccine. Vaccinations and incident HZ cases were identified by electronic health records. The hazard ratio for incident HZ associated with concomitant vs. nonconcomitant vaccination was estimated using the Cox proportional hazard model. There were 56 incident HZ cases in the concomitant vaccination cohort and 58 in the nonconcomitant vaccination cohort, yielding a HZ incidence of 4.54 (95% confidence interval [CI], 3.43-5.89) and 4.51 (95% CI, 3.42-5.83) per 1000 person-years, respectively. The hazard ratio comparing the incidence rate of HZ in the two cohorts was 1.19 (95% CI, 0.81-1.74) in the adjusted analysis. In this study, we found no evidence of an increased risk of HZ in the population receiving zoster vaccine and pneumococcal vaccine concomitantly. The revision of the product information needs to be carefully assessed to avoid introducing barriers to patients and providers who are interested in these two important vaccines.
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