Measles outbreak linked to a minority group in Austria, 2008.

We report on a measles outbreak originating in an anthroposophic community in Austria, 2008. A total of 394 (94.9%) cases fulfilled the outbreak case definition including 168 cases affiliated to the anthroposophic community. The source case was a school pupil from Switzerland. The Austrian outbreak strain was genotype D5, indistinguishable from the Swiss outbreak strain. A school-based retrospective cohort study in the anthroposophic school demonstrated a vaccine effectiveness of 97.3% in pupils who had received a single dose of measles-containing vaccine and 100% in those who had received two doses. The vaccination coverage of the cases in the anthroposophic community was 0.6%. Of the 226 outbreak cases not belonging to the anthroposophic community, the 10-24 years age group was the most affected. Our findings underline the epidemiological significance of suboptimal vaccination coverage in anthroposophic communities and in older age groups of the general population in facilitating measles virus circulation. The findings of this outbreak investigation suggest that the WHO European Region is unlikely to achieve its 2010 target for measles and rubella elimination.