Measles in Geneva between 2003 and 2010: persistence of measles outbreaks despite high immunisation coverage.

Despite high immunisation coverage, several measles outbreaks occurred in the canton of Geneva between 2003 and 2010, with 161 reported cases (52 in 2003, 16 in 2005 and 93 in 2007-2010). It affected mainly 10-14 year-old children in 2003 (31%), and adults 20 years and older in 2005 (75%) and 2007-2010 (39%). Several cases were imported from neighbouring cantons and countries, as confirmed by the diversity of the genotypes identified (D8, D6, D5, D4 and G3). Infections were mainly transmitted via family (54%) and school (22%) in 2003, hospital (71%) and family (29%) in 2005, and family (55%) and school (26%) in 2007-2010. In 2003, 6% of infected patients were vaccinated, 27% in 2005 and 2% in 2007-2010, none of them with two doses of measles-containing vaccine. Between 2003 and 2008, measles vaccine coverage, particularly for the second dose, increased by 23 percentage points to 91.7% in the 28 month-olds, by 27 points to 92.3% in the 5-6 year-olds, and by 19 points to 86% in the 13-14 year-olds. In a cosmopolitan setting where immunisation coverage is high but not sufficient to eradicate measles, outbreaks can be limited by efficient surveillance and early control measures. Catch-up vaccination needs to be reinforced among teenagers and young adults. .