Elsevier

Vaccine

Volume 29, Issue 15, 24 March 2011, Pages 2791-2796
Vaccine

Herd immunity after two years of the universal mass vaccination program against rotavirus gastroenteritis in Austria

https://doi.org/10.1016/j.vaccine.2011.01.104Get rights and content

Abstract

Austria was the first country in Europe implementing a universal mass vaccination program against rotavirus gastroenteritis (RV-GE) for all infants nationwide. Epidemiological data from a hospital based surveillance system show that incidence rates of children hospitalized with RV-GE decreased in 2009 compared to 2008 and compared to the prevaccination period 2001–2005. Decreasing hospitalization-rates from RV-GE were observed in children of all age groups, even in those not eligible for vaccination according to their age, suggesting herd immunity induced by universal mass vaccination against RV-GE. In 2009 the disease burden was highest in children below three months of age stressing the importance of the early start of the immunization course.

Introduction

Rotavirus (RV) vaccines have been available in many European countries since 2006, and as of April 2009 the Advisory Group of Experts on Immunization, World Health Organization (WHO), has recommended the general vaccination against rotavirus gastroenteritis (RV-GE) of all children worldwide [1], [2]. The positive risk-benefit-ratio of RV vaccines is undoubted and the WHO as well as the European Medicines Agency and the US Food and Drug Administration continue to recommend the use of RV vaccines [3], [4], [5].

In regard to RV vaccinations, Europe is divided: Currently, in many European countries general RV vaccination is not endorsed because of unfavorable cost-effectiveness assessment of the vaccines, such as in Switzerland [6] or Denmark [7]. In contrast, other countries like Austria [8], Belgium [9], Luxemburg [10], or Finland [11] do recommend the RV vaccination of all children.

In Austria vaccination against RV-GE was implemented in the recommendations 2006 [8]. The universal mass vaccination (UMV) started in August 2007 and consequently vaccination coverage rates increased to 87% in 2008. Concurrently a decrease of hospitalizations in the vaccinated cohort was observed: from August 2007 until December 2008 the number of hospitalized cases in children between 90 days and 20 months of age (the cohort eligible for vaccination in the course of the UMV) was reduced by 74% compared to identical periods before introduction of the vaccines, and a reduction in hospitalized cases was observed in children below 90 days of age as well, which was attributed to partial vaccination of these children [12].

The aim of the current investigation was to continue monitoring RV epidemiology in Austrian children during UMV. After roughly two years of general RV vaccination of the Austrian birth cohorts we addressed the question whether there were signs of herd immunity. Additionally, we aimed to analyse compliance with the vaccination schedule in Austria (administration of the first dose at the age of six weeks, consecutive dose(s) at interval(s) of at least four weeks depending on the RV vaccine used), and we wanted to evaluate adverse events that were reported in Austria after administration of the oral RV vaccines in 2009.

Section snippets

Study design

In Austria a surveillance system monitoring RV-GE has been initiated in 1997. In the first year cases of RV-GE were reported by all paediatric hospital wards nationwide. Starting from 1998 the surveillance system was restricted to a sentinel system covering one third of the paediatric beds in the country. It has been shown that the sentinel system is representative for Austria covering urban and rural areas [12], [13].

Hospitalized cases of RV-GE were reported by paediatricians indicating the

Incidence of rotavirus gastroenteritis

From January 1 to December 31, 2009 a total of 441 reports on hospitalized cases of RV-GE in children up to 15 years of age were received, which adds up to an extrapolated number of 1444 cases for the year 2009.

In children below 12 months of age the hospitalization rates dropped to 440.8 × 10−5 (reduction of 79% compared to 2001–2005, reduction of 30% compared to 2008). In children aged between 12 and 24 months the rate of hospitalization decreased to 408.4 × 10−5 in 2009 (reduction of 76% compared

Discussion

Impact of rotavirus vaccination is being increasingly obtained from several countries following the April 2009 WHO recommendation of universal use of these vaccines [2], [9], [21], [22], [23], [24]. By 2010, in Australia, several European countries, as well as in several Central- and Southern American countries and South Africa general RV-vaccination of all infants has been recommended [9], [23], [25], [26].

Austria is one of the very first countries in the European region using RV vaccines on a

Conclusion

The UMV against RV-GE in 2009 led to a further decrease of RV-GE associated hospitalizations in Austrian children. Decreasing numbers of cases were demonstrated not only in the vaccinated cohort, but also in children too young to get vaccinated and in those too old to have been vaccinated during UMV, indicating herd protection effects. However, in 2009 in children below five years of age the group with the highest percentage of cases were children below three months of age which underlines the

Acknowledgements

This study was supported by a grant of the Research Foundation of the Austrian National Bank (Grant No. 13229). The skilful technical assistance of Dr. Michael Hofer is gratefully acknowledged.

We would like to thank all paediatricians and the staff of the wards from all participating hospitals for their continuing support: S. Guttmann, A. Havranek, A. Gyasi, H. Steger (Vienna), P. Schabasser (Mistelbach), E. Schuster, K. F. Zwiauer (St. Pölten), I. Paier, F. Eitelberger, J. Weithaler, D.

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