UK measles outbreak in non-immune anthroposophic communities: the implications for the elimination of measles from Europe

Abstract

We describe the epidemiology of the first nationwide outbreak of measles infection in the UK since the implementation of a mass vaccination campaign. Notifications of infectious diseases, interview and postal questionnaire identified 293 clinical cases, 138 of which were confirmed by salivary IgM, measles virus isolation and PCR. Twelve were epidemiologically linked to confirmed cases. The outbreak began in London, after contact with measles infection probably imported from Italy. Measles genotyping determined by sequence analysis confirmed spread to other unimmunized anthroposophic communities in the north, south west and south coast of England. Only two cases had been vaccinated against measles infection, and 90% of cases were aged under 15 years. Measles virus can selectively target non-immune groups in countries with high vaccine uptake and broader herd immunity. Without harmonization of vaccination policies and uniform high coverage across Europe, the importation and spread of measles virus amongst non-immune groups may prevent the elimination of measles.

Measles outbreak linked to a minority group in Austria, 2008

“…It is therefore essential to understand the reasons for low vaccine uptake in certain sub-populations [19,23]. In the Austrian anthroposophic community 94 % of parents willing to give reasons for a child's unvaccinated status stated that having a measles infection is important for a child's development and has a ' beneficial strengthening effect upon the child '.…”

“…The highest reported number of cases (83 cases) was registered in calendar week 12 (17)(18)(19)(20)(21)(22)(23). Of the 394 outbreak cases, 194 (49 %) occurred in the first 4 weeks of the outbreak (13 March-6 April, calendar weeks [11][12][13][14].…”

“…Figure 1 shows the outbreak cases by day of rash onset and province of occurrence. Figure 2 depicts the regional distribution of cases by province and health districts within the first 4 weeks of the outbreak (13 March-6 April, calendar weeks [11][12][13][14] and within the following nine outbreak weeks (7 April-13 July, calendar weeks [15][16][17][18][19][20][21][22][23][24][25][26][27][28].…”

“…The official estimate of the average measles vaccine coverage with at least one dose for the birth cohorts 1997-2007 was 84 % [5]. No data were available on the age groupspecific measles seroprevalence of the Austrian population [6].…”

Networks of influence and infection: parental choices and childhood disease

“…This effect is increased when interactions are spatially local; in closely knit communities, two parents may have the same attitudes even if they do not directly influence each other. Therefore, we would expect clustered opinion to have the greatest impact when additional social factors, such as schools that serve particular religious communities (Hanratty et al 2000;May & Silverman 2003;Schmid et al 2008), result in large interacting groups of unvaccinated children. Unvaccinated children are unlikely to form clusters unless their parents are also clustered; however, clustering of parents need not lead to clustering of offspring.…”