Vaccine
http://www.sciencedirect.com/science/journal/0264410X
Volume 30, Issue 31 pp. 4581-4708 (29 June 2012)

Regular Papers
Mumps outbreak among vaccinated university students associated with a large party, the Netherlands, 2010
Original Research Article
Pages 4676-4680
Katie Greenland, Jane Whelan, Ewout Fanoy, Marjon Borgert, Koen Hulshof, Kioe-Bing Yap, Corien Swaan, Tjibbe Donker, Rob van Binnendijk, Hester de Melker, Susan Hahn

Abstract
We investigated a mumps outbreak within a highly vaccinated university student population in the Netherlands by conducting a retrospective cohort study among members of university societies in Delft, Leiden and Utrecht. We used an online questionnaire asking for demographic information, potential behavioural risk factors for mumps and the occurrence of mumps. Vaccine status from the national vaccination register was used. Overall, 989 students participated (20% response rate). Registered vaccination status was available for 776 individuals, of whom 760 (98%) had been vaccinated at least once and 729 (94%) at least twice. The mumps attack rate (AR) was 13.2% (95%CI 11.1–15.5%). Attending a large student party, being unvaccinated and living with more than 15 housemates were independently associated with mumps ((RR 42 (95%CI 10.1–172.4); 3.1 (95%CI 1.7–5.6) and 1.8 (95%CI 1.1–3.1), respectively). The adjusted VE estimate for two doses of MMR was 68% (95%CI 41–82%). We did not identify additional risk factors for mumps among party attendees. The most likely cause of this outbreak was intense social mixing during the party and the dense communal living environment of the students. High coverage of MMR vaccination in childhood did not prevent an outbreak of mumps in this student population.