Elsevier

Vaccine

Volume 22, Issues 29–30, 28 September 2004, Pages 3947-3951
Vaccine

Epidemiology of severe varicella–zoster virus infection in Spain

https://doi.org/10.1016/j.vaccine.2004.04.004Get rights and content

Abstract

Data of hospitalizations for varicella and herpes zoster in Spain during the 1999–2000 period were obtained from the national surveillance system for hospital data. A total of 3083 hospitalizations for varicella and 6324 for herpes zoster were identified, representing an annual incidence of 4.1 and 8.4 per 100,000 persons per year, respectively. Almost half of patients hospitalized for varicella were children under 5 years of age. In contrast, 78% of hospitalizations for zoster occurred in adults >50 years of age. Hospitalizations for varicella and herpes zoster resulted annually in 11,141 and 40,090 days of hospitalization and a cost of € 3.2 and 7.0 million, respectively.

Introduction

Primary Varicella–zoster virus (VZV) infection results in varicella (chickenpox), a common and extremely contagious acute infection that occurs in epidemics among pre-school and school-aged children [1], [2]. The preponderance of uncomplicated childhood cases has tended to overshadow the morbidity and mortality associated with severe cases and the resultant hospitalizations [3], [4]. Children bear the brunt of the health burden, however, the risk of severe complications and death is higher among susceptible adolescents, adults, and immunocompromised individuals [5]. Reactivation of latent VZV from dorsal root ganglia results in herpes zoster (shingles), which is more common and more severe in the elderly and immunocompromised persons [1], [2]. Complications of zoster occur in 13–26% of cases, being post-herpetic neuralgia—the most common and debilitating [6].

The availability of an effective, live, and attenuated varicella vaccine underlines the need to better understand the burden of this disease. Population-based surveys carried out in the United States demonstrated the extent of varicella morbidity, complications and overall cost of this disease. These studies provided the rationale for adopting a policy of routine immunization of healthy children in 1996 [7], [8], [9], [10], [11], [12]. However, epidemiologic data gathered in one part of the world may not reflect the situation in other parts of the world. The live and attenuated varicella vaccine has been licensed in many countries and some of them are currently considering whether to include varicella vaccine into their routine immunization schedule. To determine the most appropriate strategies and to evaluate the overall impact and cost-effectiveness of varicella immunization programs, a good understanding of the pre-vaccine epidemiology of both primary and reactivated varicella–zoster virus infection is crucial.

Hospital discharge databases provide a complete record of all hospitalizations and are not subject to under-diagnosis and deficiencies in reporting that limit surveillance systems of outpatient diseases. Additionally, hospitalization databases measure the most severe part of the disease spectrum [13]. The aim of this study was to obtain population-based estimates of varicella and zoster hospitalizations in Spain, and to estimate the annual costs of these hospital admissions.

Section snippets

Methods

Varicella and zoster hospitalization in Spain during 1999–2000 were obtained from the national surveillance system for hospital data (Conjunto Mı́nimo de Datos; CMBD), that collects information on all hospital discharges and uses clinical codes from the Spanish version of the Ninth International Classification of Diseases (Modificación Clı́nica Clasificación Internacional de Enfermedades; CIE-9-MC). This nationwide system involves approximately 95% of public hospitals [14], [15]. Information on

Results

A total of 3083 hospitalizations for primary varicella and 6324 herpes zoster-related hospital admissions were identified during the 2-year study period. Herpes zoster was the first-listed diagnosis in 1903 cases (428 had underlying conditions) and varicella in 2114 cases (113 with underlying conditions). The age-specific number of hospitalizations and hospitalization rates are shown in Table 1, Table 2 (zoster). The average annual incidence of hospitalizations for varicella and zoster was 4.1

Discussion

The annual incidence of hospitalizations for primary varicella and herpes zoster in Spain was 4.1 per 100,000 population and 8.4 per 100,000 population, respectively. Varicella figures are similar to those obtained in studies carried out in the United States during a 10-year period from 1986 to 1995 (4.1 per 100,000 population) and in England and Wales during 1991–2000 (4.5 per 100,000 population). By contrast, the incidence of zoster-related hospitalizations varies widely within the different

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