A vaccine to prevent shingles may reduce by half the occurrence of this painful skin and nerve infection in older people (aged over 65 years) and may also reduce the rate of a painful complication of shingles, but has a very low uptake (only 4%) in older adults in the United States.
Herpes zoster (“a.k.a. “shingles”) is a significant public health problem affecting 1 million individuals in the USA each year and associated with important illness. Herpes zoster occurs following reactivation of latent varicella zoster virus (VZV) infection and presents with a painful vesicular rash, which frequently in older individuals leads to prolonged pain, post-herpetic neuralgia (PHN), with a major impact on quality of life. Vaccine efficacy has been shown in trials; in a selected insured population; and among people with any of five specific immune-mediated diseases but not among an unselected population in a clinical setting.
Despite Advisory Committee for Immunization Practices (ACIP) recommendations, individuals with immunosuppression received the live herpes zoster vaccine in clinical practice. The lack of adherence to ACIP recommendations on vaccination is not entirely surprising given that individuals with immunosuppression are not only at increased risk of incident herpes zoster but also at significantly increased risk of herpes zoster complications, in particular prolonged, severe PHN. Previous research has suggested that the varicella vaccine may be efficacious and safe in people with immunosuppressive disorders. Similar evidence about vaccine effectiveness (VE) is lacking in relation to the zoster vaccine in individuals with serious immune suppression, beyond effectiveness among those with the selected immune-mediated disorders examined to date.
Important outstanding research questions with great relevance to policy include VE in unselected population-based elderly US populations; this includes effectiveness against PHN, which has not been assessed in routine practice. This is the first study to the best of our knowledge to assess the effectiveness of herpes zoster vaccine against both incident herpes zoster and PHN in an unselected older population including those with immunosuppression.
Herpes Zoster Vaccine Effectiveness against Incident Herpes Zoster and Post-herpetic Neuralgia in an Older US Population: A Cohort Study. (2013) PLoS Med 10(4): e1001420. doi:10.1371/journal.pmed.1001420
Herpes zoster is common and has serious consequences, notably post-herpetic neuralgia (PHN). Vaccine efficacy against incident zoster and PHN has been demonstrated in clinical trials, but effectiveness has not been studied in unselected general populations unrestricted by region, full health insurance coverage, or immune status. Our objective was to assess zoster vaccine effectiveness (VE) against incident zoster and PHN in a general population-based setting. A cohort study of 766,330 fully eligible individuals aged over 65 years was undertaken in a 5% random sample of Medicare who received and did not receive zoster vaccination between 1st January 2007 and 31st December 2009. Incidence rates and hazard ratios for zoster and PHN were determined in vaccinated and unvaccinated individuals. Analyses were adjusted for age, gender, race, low income, immunosuppression, and important comorbidities associated with zoster, and then stratified by immunosuppression status. Adjusted hazard ratios were estimated using time-updated Cox proportional hazards models. Vaccine uptake was low (3.9%) particularly among black people (0.3%) and those with evidence of low income (0.6%). 13,112 US Medicare beneficiaries developed incident zoster; the overall zoster incidence rate was 10.0 (9.8–10.2) per 1,000 person-years in the unvaccinated group and 5.4 (95% CI 4.6–6.4) per 1,000 person-years in vaccinees, giving an adjusted VE against incident zoster of 0.48 (95% CI 0.39–0.56). In immunosuppressed individuals, VE against zoster was 0.37 (95% CI 0.06–0.58). VE against PHN was 0.59 (95% CI 0.21–0.79). Vaccine uptake was low with variation in specific patient groups. In a general population cohort of older individuals, zoster vaccination was associated with reduction in incident zoster, including among those with immunosuppression. Importantly, this study demonstrates that zoster vaccination is associated with a reduction in PHN.