Modeling the durability of ZOSTAVAX® vaccine efficacy in people ≥60 years of age

Xiaoming Li, Jane H. Zhang, Robert F. Betts, Vicki A. Morrison, Ruifeng Xu, Robbin F. Itzler, Camilo J. Acosta, Erik J. Dasbach, James M. Pellissier, Gary R. Johnson, Ivan S.F. Chan

Research output: Contribution to journalArticlepeer-review

18 Scopus citations


Since 2006, the vaccine, ZOSTAVAX®, has been licensed to prevent herpes zoster. Only limited clinical follow-up data are available to evaluate duration of protection, an important consideration when developing HZ vaccination policy recommendations. Four Poisson regression models were developed based on an integrated analysis of data from the Shingles Prevention Study and its Short Term Persistence extension to estimate the effects of years-since-vaccination and chronological-age on vaccine efficacy among people ≥60 years old. The models included number of HZ cases parsed into categories by chronological-age and time-since-vaccination as the dependent variable with different explanatory variables in each model. In all models, the interaction between vaccine-group and chronological-age was statistically significant indicating that vaccine efficacy decreases with the expected effects of advancing age but the interaction between vaccine-group and time-since-vaccination was not statistically significant indicating that much of the reduction in vaccine efficacy over time-since-vaccination can be explained by increasing age.

Original languageEnglish (US)
Pages (from-to)1499-1505
Number of pages7
Issue number12
StatePublished - Mar 17 2015

Bibliographical note

Funding Information:
This study was funded by Merck & Co., Inc. (sponsor). Although the sponsor formally reviewed a penultimate draft, the opinions expressed are those of the authorship and may not necessarily reflect those of the sponsor. All co-authors approved the final version of the manuscript.

Publisher Copyright:
© 2015.


  • Concurrent age effect
  • Durability
  • Herpes zoster
  • Poisson regression
  • Time effect
  • Vaccine efficacy
  • Zoster vaccine


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