MEASLES OUTBREAKS IN THE UNITED-STATES, 1987 THROUGH 1990

Background. During 1989 and 1990 reported measles cases in the United States increased 6- to 9-fold over the annual mean of 3000 between 198 5 and 1988. To evaluate recent epidemiology we summarized measles outb reaks. Methods. Confirmed measles cases reported to the National Notif iable Disease Surveillance System during 1987 through 1990 were analyz ed, An outbreak was defined as greater than or equal to 5 epidemiologi cally linked cases. Results. There were 815 outbreaks, accounting for 94% of the 52 846 cases reported, Similar to 1985 and 1986, 3 patterns of measles transmission during outbreaks were identified: (1) predomi nantly among unvaccinated pre-school age children <5 years of age (38% of outbreaks); (2) predominantly among vaccinated school age children 5 to 17 years of age (40%); and (3) predominantly among unvaccinated and vaccinated post-school age persons greater than or equal to 18 yea rs of age (22%), Most outbreaks were small (median, 12 cases), but ver y large outbreaks occurred (maximum size, 10670), Although school age outbreaks (58%) predominated during 1987 and 1988, preschool age (40%) and post-school age (23%) outbreaks were more important during 1989 a nd 1990. Conclusions, Recent epidemiology suggests that to achieve eli mination of measles, ACIP recommendations must be fully implemented, i ncluding (1) routine administration of the first dose of measles vacci ne from 12 to 15 months of age and (2) use of a routine two-dose sched ule to prevent school age and post-school age outbreaks.