Smoking and older age associated with mumps in an outbreak in a group of highly-vaccinated individuals attending a youth club party, the Netherlands, 2012.

G Ladbury,H Boot,S Ostendorf,T Waegemaekers,R Van Binnendijk,S Hahné

doi:10.2807/1560-7917.es2014.19.16.20776

Abstract

We describe a mumps outbreak in a highly-vaccinated population attending a party at a youth club. In a retrospective cohort study with 60 of approximately 100 participants responding, vaccination status was verified for 58/59 respondents, of whom 54 were vaccinated twice and four once. The attack rate was 22% (13 cases, all vaccinated), with smoking at the party (risk ratio (RR) 3.1; 95% confidence interval (CI): 1.6–6.0, p=0.001) and age ≥21 years (RR 4.7; 95% CI: 2.1–10.2, p<0.0001) as risk factors for disease in the binominal regression analysis. Mild upper respiratory illness was also highly prevalent in those who did not meet the mumps case definition (n=46) after the party, suggesting that mumps virus infection may cause mild disease in vaccinated individuals. Our investigation adds toevidence that crowded social events and smoking may facilitate spread of mumps virus among vaccinated populations, with waning immunity playing a role. The suggestion that mumps virus infection in vaccinated individuals may manifest as mild upper respiratory illness could have implications for transmission and warrants further investigation.

Highlights

Mumps is caused by a paramyxovirus infection and is characterised by acute swelling of the parotid and other salivary glands
None of the Figure Number of cases of mumps associated with attending a village youth club party on 9 March 2012, by date of symptom onset, the Netherlands, March–April 2012 (n=11)
We describe a mumps outbreak with a 22% attack rates (AR) following a party at a youth club where over 90% of outbreak investigation participants had received two doses of MMR vaccine

Summary

Introduction

Mumps is caused by a paramyxovirus infection and is characterised by acute swelling of the parotid and other salivary glands. Routine mumps vaccination has been implemented in the Netherlands since a measles-mumpsrubella (MMR) vaccine containing the Jeryl Lynn virus strain was introduced into the National Immunisation Programme in 1987. This vaccine is offered as a twodose schedule at 14 months and nine years of age. Vaccination coverage with two doses has consistently exceeded 93% [1], several outbreaks in highly vaccinated populations have occurred recently, in students [2,3,4]. These incidents contribute to growing evidence that high vaccine coverage may not suffice to prevent outbreaks [5,6]

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