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, 8 (6), e66485

Herpes Zoster Risk Reduction Through Exposure to Chickenpox Patients: A Systematic Multidisciplinary Review


Herpes Zoster Risk Reduction Through Exposure to Chickenpox Patients: A Systematic Multidisciplinary Review

Benson Ogunjimi et al. PLoS One.


Varicella-zoster virus (VZV) causes chickenpox and may subsequently reactivate to cause herpes zoster later in life. The exogenous boosting hypothesis states that re-exposure to circulating VZV can inhibit VZV reactivation and consequently also herpes zoster in VZV-immune individuals. Using this hypothesis, mathematical models predicted widespread chickenpox vaccination to increase herpes zoster incidence over more than 30 years. Some countries have postponed universal chickenpox vaccination, at least partially based on this prediction. After a systematic search and selection procedure, we analyzed different types of exogenous boosting studies. We graded 13 observational studies on herpes zoster incidence after widespread chickenpox vaccination, 4 longitudinal studies on VZV immunity after re-exposure, 9 epidemiological risk factor studies, 7 mathematical modeling studies as well as 7 other studies. We conclude that exogenous boosting exists, although not for all persons, nor in all situations. Its magnitude is yet to be determined adequately in any study field.

Conflict of interest statement

Competing Interests: BO and PB report no conflicts of interest. PVD acts as (principal) investigator for vaccine trials (including herpes zoster vaccine trials) conducted on behalf of the University of Antwerp, for which the University obtains research grants from vaccine manufacturers. PVD receives no personal remuneration for this work. This does not alter the authors' adherence to all the PLOS ONE policies on sharing data and materials.


Figure 1
Figure 1. Modified PRISMA flow diagram.
PubMed and Web of Science (WoS) search results were combined and after controlling for duplicates, titles and abstracts from references were screened for further full text assessment. Citations from and to the selected references were also screened using title and abstract for further full text assessment. Citations from and to the additional selected references were again screened as discussed. The additional selected references thus found were added to the earlier found references in order to obtain the Selected Total.

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Grant support

BO thanks the Research Foundation Flanders (FWO) for the financial support he has received. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.