Despite long-standing two-dose measles-mumpsrubella (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. ; The authors would like to acknowledge the colleagues of the Flemish Agency for Care and Health, the Scientific Institute of Public Health and the measles elimination committee for fruitful discussions related to this research. NH acknowledges support of the University of Antwerp Scientific Chair in Evidence-based Vaccinology sponsored in 2009-2014 by a gift from Pfizer. SA acknowledges support by the Research Fund of Hasselt University (Grant BOF11NI31). ES and HG acknowledge support from a Methusalem research grant from the Flemish government. NG is beneficiary of a postdoctoral grant from the AXA Research Fund. Support from the IAP Research Network P7/06 of the Belgian State (Belgian Science Policy) is gratefully acknowledged. HT and EL are postdoctoral ...