2 INDEPENDENT OUTBREAKS OF MEASLES IN PARTIALLY VACCINATED JUNIOR-HIGH-SCHOOLS IN TOTTORI, JAPAN

We analyzed retrospectively a relative risk of measles attacks in vacc inated vs. unvaccinated students using two independent outbreaks in Ja pan. The first involved 33/328 (10%) students where 64% students and 3 0% measles cases had been vaccinated. The second involved 27/241 (11%) students where 81% students and 48% measles cases had been vaccinated . The attack rates of vaccinated vs. unvaccinated students were signif icantly low (p < 0.001), but they accounted 25% in both episodes. The statistically significant clinical features among vaccinated and unvac cinated cases included the average duration of fever, 5.16 +/- 1.71 vs . 6.67 +/- 2.19 days (p = 0.01) and the incidence of complications, 0 vs. 25%, respectively. These results suggested that the measles in vac cinated cases were mostly due to secondary failures.