From January to February 2005, the healthcare authorities of the Canton of Geneva were alerted to 15 cases of measles, in contrast to one single case in 2004. The adult status (17-44 years) of the affected persons years was unusual. Four were health care workers at the same hospital who were infected after contact with a 44-year-old patient in a single night during his stay in the emergency room. The presumption that measles are only a paediatric disease had made the diagnosis difficult. None of all these adults was immune according to the actual recommendations. Despite a federal vaccine policy, repetition of recommendations, good results of available vaccines and reimbursement of the cost by health insurance companies, voluntary vaccination prevalence is too small in Switzerland to prevent the outbreak of epidemics. In contrast to the goals of the World Health Organization (WHO) and the Swiss Federal Office of Public Health, the country is unfortunately far from displaying a sufficiently high herd immunity to prevent health care-associated and economic damage by sporadic epidemics.