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Measles outbreaks in the United States, 1987 through 1990
S Hutchins1, L Markowitz, W Atkinson
1National Immunization Program, Centers for Disease Control and Prevention, Atlanta, GA, USA.
Background:
During 1989 and 1990 reported measles cases in the United States increased 6- to 9-fold over the annual mean of 3000 between 1985 and 1988. To evaluate recent epidemiology we summarized measles outbreaks.
Methods:
Confirmed measles cases reported to the National Notifiable Disease Surveillance System during 1987 through 1990 were analyzed. An outbreak was defined as > or = 5 epidemiologically 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) predominantly 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 > or = 18 years of age (22%). Most outbreaks were small (median, 12 cases), but very large outbreaks occurred (maximum size, 10,670). Although school age outbreaks (58%) predominated during 1987 and 1988, preschool age (40%) and post-school age (23%) outbreaks were more important during 1989 and 1990.
Conclusions:
Recent epidemiology suggests that to achieve elimination of measles, ACIP recommendations must be fully implemented, including (1) routine administration of the first dose of measles vaccine from 12 to 15 months of age and (2) use of a routine two-dose schedule to prevent school age and post-school age outbreaks.
Insights
Measles outbreaks surged in the US, primarily affecting unvaccinated preschoolers and vaccinated school-aged children. Implementing a two-dose measles vaccine schedule is crucial for elimination.
Area of Science:
- Epidemiology
- Public Health
- Vaccinology
Background:
- Reported measles cases in the US saw a 6- to 9-fold increase in 1989-1990 compared to prior years.
- This surge prompted an evaluation of recent measles outbreak epidemiology.
Purpose of the Study:
- To analyze the epidemiology of measles outbreaks in the United States between 1987 and 1990.
- To identify patterns of measles transmission during outbreaks.
Main Methods:
- Analysis of confirmed measles cases reported to the National Notifiable Disease Surveillance System (NNDSS) from 1987-1990.
- Definition of a measles outbreak as five or more epidemiologically linked cases.
Main Results:
- 815 measles outbreaks accounted for 94% of the 52,846 reported cases.
- Three transmission patterns were observed: unvaccinated preschool-aged children (<5 years), vaccinated school-aged children (5-17 years), and unvaccinated/vaccinated post-school-aged persons (≥18 years).
- Preschool and post-school age outbreaks became more prominent in 1989-1990 compared to earlier years.
Conclusions:
- Achieving measles elimination requires full implementation of Advisory Committee on Immunization Practices (ACIP) recommendations.
- Key recommendations include routine first-dose measles vaccination at 12-15 months and a two-dose schedule to prevent outbreaks in school-aged and post-school-aged populations.