Perspectives on the Impact of Varicella Immunization on Herpes Zoster. A Model-Based Evaluation from Three European Countries

DONDENA Centre for Research on Social Dynamics, Bocconi University, Milan, Italy.
PLoS ONE (Impact Factor: 3.53). 04/2013; 8(4):e60732. DOI: 10.1371/journal.pone.0060732
Source: PubMed

ABSTRACT The introduction of mass vaccination against Varicella-Zoster-Virus (VZV) is being delayed in many European countries because of, among other factors, the possibility of a large increase in Herpes Zoster (HZ) incidence in the first decades after the initiation of vaccination, due to the expected decline of the boosting of Cell Mediated Immunity caused by the reduced varicella circulation. A multi-country model of VZV transmission and reactivation, is used to evaluate the possible impact of varicella vaccination on HZ epidemiology in Italy, Finland and the UK. Despite the large uncertainty surrounding HZ and vaccine-related parameters, surprisingly robust medium-term predictions are provided, indicating that an increase in HZ incidence is likely to occur in countries where the incidence rate is lower in absence of immunization, possibly due to a higher force of boosting (e.g. Finland), whereas increases in HZ incidence might be minor where the force of boosting is milder (e.g. the UK). Moreover, a convergence of HZ post vaccination incidence levels in the examined countries is predicted despite different initial degrees of success of immunization policies. Unlike previous model-based evaluations, our investigation shows that after varicella immunization an increase of HZ incidence is not a certain fact, rather depends on the presence or absence of factors promoting a strong boosting intensity and which might or not be heavily affected by changes in varicella circulation due to mass immunization. These findings might explain the opposed empirical evidences observed about the increases of HZ in sites where mass varicella vaccination is ongoing.

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    The Journal of infection 11/2013; DOI:10.1016/j.jinf.2013.09.035 · 4.13 Impact Factor
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    ABSTRACT: Varicella vaccines are highly immunogenic, efficacious and safe in preventing varicella disease. The United States has been the first country recommending universal vaccination. In the EU/EEA countries, the use of varicella vaccine is heterogeneous, with some countries recommending universal vaccination in children at national or regional level, others only in high risk groups and others having no recommendation at all. Uncertainties on the potential impact of varicella vaccination on the epidemiology of varicella and herpes zoster still exist. These uncertainties are the main reason behind the diverse vaccine recommendations. Surveillance systems and mathematical models could be useful to address these uncertainties. However, the lack of surveillance of varicella and HZ in some countries, as well as the high variability of surveillance systems in the countries that have one, makes it difficult to assess the effect of the vaccine. On the other side, mathematical models are based on assumptions and should be interpreted carefully. Continuous surveillance of varicella and herpes zoster is needed in order to identify any changes in the epidemiological presentation of the diseases. In any case, continuous surveillance will be needed to fully describe the impact of the programmes currently running and clarify some of the actual uncertainties in the near future. Additionally, increasing our understanding of the risk factors for development of HZ is required. This article is protected by copyright. All rights reserved.
    Clinical Microbiology and Infection 02/2014; DOI:10.1111/1469-0691.12580 · 4.58 Impact Factor
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    ABSTRACT: Introduction The reactivation of the varicella-zoster virus in adults causes a rash known as herpes-zoster. Complications affecting the central nervous system and can cause postherpetic neuralgia. Objective To evaluate the efficacy and safety of the vaccine for the prevention of re-infection by varicella-zoster virus in adults. Methods Systematic review of the literature (2005-2013). A literature search was performed in electronic databases such MedLine or Embase, and hand search in journals. Inclusion criteria were clinical trials in adults vaccinated against herpes-zoster, recording results of efficacy and safety. Quality of the studies was assessed by CASPe checklist. Results Twelve clinical trials of moderate quality were included. The ranges of antibody titters (GMT) were higher in the vaccinated group compared to placebo (471-810 vs. 292-391 gpELISA/mL). GMFR ranges were also higher (2.3-1.9 vs. 1). Vaccination reduced the incidence of herpes zoster, with a protective efficacy of 51-70%. Local adverse effects (60% vs. 14.7%) and systemic (13% vs. 8%) were higher in the vaccinated groups, the most frequent reactions pain, redness, and swelling. Serious adverse events and deaths were not different between groups. Conclusions The vaccine against herpes-zoster shows good efficacy and safety profile. Vaccine has good immunogenicity and reduces the incidence of herpes zoster and postherpetic neuralgia. Serious adverse effects are rare and occur similarly in studied groups.
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Jun 1, 2014