MEASLES OUTBREAKS IN THE CANTON OF BERNE

Currently, overall vaccination coverage against measles among infants ranges between 77% and 89% in Switzerland. Experience in other countri es has shown that this level of vaccination is not sufficient to preve nt measles outbreaks, especially among schoolchildren. During 1992 sur veillance for measles outbreaks in closed populations was conducted in the Canton of Berne. Outbreaks were investigated for vaccine efficacy .Two measles outbreaks in schoolchildren were observed during the stud y period. In 2 Bernese suburban schools 6 measles cases in children (m edian age 12.5 years) occurred over a period of 37 days. One of the ca ses had been vaccinated. Vaccination rate in the healthy control child ren was 89.7%. Estimated vaccine efficacy was 97.7% (95% confidence in terval [CI]: 68%, 99%). The second outbreak occurred in a rural region and comprised 21 measles cases (median age 7.5 years) within 43 days. 10 (47.6%) of the cases attended the same school. None of the cases h ad been vaccinated. Of the healthy control children 82.6% had received measles vaccine. Estimated vaccine efficacy was 100% (CI: 87%, 100%). These two measles outbreaks were due to failure to vaccinate rather t han low vaccine efficacy. Surveillance for measles cases is currently not sufficient for the detection of measles outbreaks in our populatio n. Laboratory confirmation of measles, especially in vaccinated person s, has become more important in a time of relatively low measles incid ence.