ASSESSING THE RISK OF MEASLES RESURGENCE IN A HIGHLY VACCINATED POPULATION: BELGIUM ANNO 2013

Saturday, 10th of January 2015

ASSESSING THE RISK OF MEASLES RESURGENCE IN A HIGHLY VACCINATED POPULATION: BELGIUM ANNO 2013

Eurosurveillance, Volume 20, Issue 1, 08 January 2015

Research articles

 

N Hens ()^1,2, S Abrams¹, E Santermans¹, H Theeten³, N Goeyvaerts^1,2, T Lernout³, E Leuridan³, K Van Kerckhove¹, H Goossens⁴, P Van Damme³, P Beutels^2,5

1. Interuniversity Institute for Biostatistics and statistical Bioinformatics, Hasselt University, Hasselt, Belgium
2. Centre for Health Economic Research and Modelling Infectious Diseases, Vaccine and Infectious Disease Institute (WHO Collaborating Centre), University of Antwerp, Antwerp, Belgium
3. Centre for the Evaluation of Vaccination, Vaccine and Infectious Disease Institute (WHO Collaborating Centre), University of Antwerp, Antwerp, Belgium
4. Laboratory of Medical Microbiology, Vaccine and Infectious Disease Institute (WHO Collaborating Centre), University of Antwerp, Antwerp, Belgium
5. School of Public Health and Community Medicine, The University of New South Wales, Sydney, Australia

Citation style for this article: Hens N, Abrams S, Santermans E, Theeten H, Goeyvaerts N, Lernout T, Leuridan E, Van Kerckhove K, Goossens H, Van Damme P, Beutels P. Assessing the risk of measles resurgence in a highly vaccinated population: Belgium anno 2013. Euro Surveill. 2015;20(1):pii=20998. Available online: http://www.eurosurveillance.org/ViewArticle.aspx?ArticleId=20998
Date of submission: 01 February 2014

Abstract and introduction below; full text, with tables and equations, is at http://www.eurosurveillance.org/ViewArticle.aspx?ArticleId=20998

Despite long-standing two-dose measles-mumps-rubella (MMR) vaccination, measles outbreaks still occur in highly vaccinated European populations. For instance, large measles outbreaks occurred in France (2008–13), the United Kingdom (2012–13) and the Netherlands (2012). Based on a multicohort model approach, using spatial serological survey data, MMR vaccination coverage data and data on social contacts, we found effective reproduction numbers significantly higher than 1 for measles in Belgium. This indicates that at one of the expected re-introductions, a measles outbreak is likely to spread, especially when it occurs during school term. The predicted average effective reproduction number increased over a 30-year time span from 1.3 to 2.2 and from 1.9 to 3.2 for basic reproduction numbers of 12 and 18, respectively. The expected relative measles incidence was highest in infants under one year of age, in adolescents and young adults. In conclusion, gradually increasing proportions of susceptible adolescents and young adults provide through their highly active social life an avenue for measles to resurge in large outbreaks upon re-introduction in Belgium, especially during school terms. Infants form an important vulnerable group during future measles outbreaks.

Introduction

A large-scale measles outbreak in France started in 2008, with more than 20,000 reported measles cases by 2013 (see e.g. [1]). In 2012 and 2013, large-scale measles outbreaks have also been reported in the Netherlands [2] and the United Kingdom (UK) [3,4]. To date, no large measles outbreaks have been reported in Belgium since the start of the two-dose vaccination programme in 1995, although some small outbreaks occurred in specific subpopulations. In 2007 and 2008, an outbreak was reported in orthodox Jewish communities [5]. In 2011, a measles outbreak started in a day-care centre and spread to anthroposophic schools, where vaccination coverage was low [6]. It is of interest to determine whether a potential for a resurgence of measles in Belgium still exists. Typically, serological data are used to determine the age-specific susceptibility profile of the population of interest. However, proper quantification of the risk of a possible resurgence based solely on such serological data is only possible if these data are recently collected and if the probability of transmission can be assumed to be independent of age.

Since there are no such recent serological data for Belgium, we apply a newly developed multicohort model [7] that allows using available serological data not necessarily collected at the calendar time of interest. In this approach, the serological data are combined with data on vaccination coverage and data on social contacts. These data are supplemented by estimates of the duration of maternal immunity and of primary and secondary vaccine failure, which were obtained from extensive literature reviews with meta-analysis.