Estimation of the burden of varicella in Europe before the introduction of universal childhood immunization

Margarita Riera-Montes,Ulrich Heininger,Thomas Verstraeten,Angel Gil,Giovanni Gabutti,Grazina Mirinaviciute,Kaatje Bollaerts,Audrey Souverain,Bayad Nozad,Elmira Flem,Susanne Hartwig,Niel Hens

doi:10.1186/s12879-017-2445-2

Abstract

BackgroundVaricella is generally considered a mild disease. Disease burden is not well known and country-level estimation is challenging. As varicella disease is not notifiable, notification criteria and rates vary between countries. In general, existing surveillance systems do not capture cases that do not seek medical care, and most are affected by underreporting and underascertainment. We aimed to estimate the overall varicella disease burden in Europe to provide critical information to support decision-making regarding varicella vaccination.MethodsWe conducted a systematic literature review to identify all available epidemiological data on varicella IgG antibody seroprevalence, primary care and hospitalisation incidence, and mortality. We then developed methods to estimate age-specific varicella incidence and annual number of cases by different levels of severity (cases in the community, health care seekers in primary care and hospitals, and deaths) for all countries belonging to the European Medicines Agency (EMA) region and Switzerland.ResultsIn the absence of universal varicella immunization, the burden of varicella would be substantial with a total of 5.5 million (95% CI: 4.7–6.4) varicella cases occurring annually across Europe. Variation exists between countries but overall the majority of cases (3 million; 95% CI: 2.7–3.3) would occur in children <5 years. Annually, 3–3.9 million patients would consult a primary care physician, 18,200–23,500 patients would be hospitalised, and 80 varicella-related deaths would occur (95% CI: 19–822).ConclusionsVaricella disease burden is substantial. Most cases occur in children <5 years old but adults require hospitalisation more often and are at higher risk of death. This information should be considered when planning and evaluating varicella control strategies. A better understanding of the driving factors of country-specific differences in varicella transmission and health care utilization is needed. Improving and standardizing varicella surveillance in Europe, as initiated by the European Centre for Disease Prevention and Control (ECDC), is important to improve data quality to facilitate inter-country comparison.

Highlights

Varicella is generally considered a mild disease
Systematic literature review Search strategy A PubMed search was conducted for peer-reviewed publications reporting primary incidence, mortality or seroprevalence data in any language in countries under the European Medicines Agency (EMA) plus Swizerland
Systematic literature review The literature search was conducted in PubMed on October 2nd 2015

Summary

Introduction

Varicella is generally considered a mild disease. Disease burden is not well known and country-level estimation is challenging. Varicella Zoster Virus (VZV) is a double-stranded DNA virus of the herpes virus family [1]. It causes varicella (chickenpox), a highly communicable disease which is usually contracted in early childhood, typically affecting children 2–8 years of age [1]. Varicella is usually a mild disease, but can cause complications requiring hospitalisation [2, 3] and, in rare instances, can even be fatal [4]. Viral reactivation, which usually occurs with increased age or immunosuppression, causes herpes zoster (shingles). Shingles is a painful condition associated with complications including postherpetic neuralgia and cerebrovascular disease [1]

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