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

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 to evidence 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.

Mumps transmission in social networks: a cohort study

“…This is higher than the 2% symptomatic mumps AR found in a large serological study, especially when considering the much longer follow-up period of the latter study (average 26 months) [5]. The AR we found is, however, much lower than the ARs of 13% and 22% found in outbreaks of mumps affecting adolescent populations with a similar vaccination coverage [9, 12]. The median age of participants to our study (23 years) matched the age of cases of mumps during the epidemic, with the majority being 18–25 years [3].…”

“…This is therefore not an explanation for the difference in ARs. The key characteristic of the outbreaks with a high AR was that they occurred among attendees of a party [9, 12]. This suggests particular circumstances favouring transmission occurred during these parties that were not present in our networks around a mumps case, even though a relatively large proportion of our participants did attended social gatherings and parties.…”

Letter to the Editor: 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

“…In their recent article, Ladbury et al present an investigation of an outbreak of mumps in a highly vaccinated group attending a youth club party in March 2012 [1]. The article suggested that crowded social events and smoking may facilitate spread of mumps virus among a highly vaccinated population and that waning immunity may also play a role.…”

Visual tools to assess the plausibility of algorithm-identified infectious disease clusters: an application to mumps data from the Netherlands dating from January 2009 to June 2016

“…To apply and assess the tools that we develop, we use mumps notification and sequence data reported between 2009 and mid-2016 in the Netherlands. We specifically chose mumps in the Netherlands as it has been intensively studied over the past few years, with comprehensive documentation available [28][29][30][31][32][33]. In the Netherlands, mumps is a notifiable disease and symptomatic cases are reported to the MHS by physicians and/or laboratories.…”