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Measles Vaccination Levels among Selected Groups of Preschool-Aged Children -- United States

In 1989 and 1990, the incidence of measles increased dramatically among preschool-aged children in inner cities (1). The largest outbreaks occurred primarily among unvaccinated black and Hispanic children in large cities (e.g., Chicago (2), Dallas, Houston, Los Angeles, Milwaukee, and New York). However, measles outbreaks have not occurred in all large U.S. cities; differences in vaccine coverage could account for these variations. This report describes surveys of vaccination levels among nonrandomly selected first- and fifth-grade students in Boston, part of New York City (Bronx), Cleveland, Houston, Jersey City, Philadelphia, Pittsburgh, and Seattle.

In May 1990, CDC and public health officials determined vaccine coverage in preschool-aged children in eight cities with differing incidences of measles during the 1980s. School records of first and fifth graders were reviewed in each city (the number of records for each grade by city ranged from 680 to 1460); completion of measles vaccination by the second birthday was the primary measure of vaccination coverage. Local officials selected the schools surveyed. Schools were classified as public or private; inner-city* or noninner-city; and black, white, or Hispanic if one of these racial/ethnic groups accounted for greater than 75% of the students (the remaining schools were classified as mixed). In grades with less than 60 students, all records were reviewed; in grades with greater than or equal to 60 students, systematic samples of records were reviewed.

Crude measles vaccine coverage levels by the second birthday ranged from 50% in both first and fifth graders selected in Jersey City to almost 90% among both groups selected in Pittsburgh (Figure 1). Within each city, the percentage of children in the first grade who were vaccinated against measles by the second birthday was similar to or higher than that of children in the fifth grade.

Among first-grade students in each of the seven cities in which both private and public schools were surveyed, the percentage of children who were vaccinated by the second birthday was greater in private schools. The differences were statistically significant for all areas except Bronx and Seattle. In five of the six cities in which schools in noninner-city areas were surveyed, the percentage of children who were vaccinated was greater in noninner-city than in inner-city schools (Table 1).

Within inner-city public schools in the same cities, measles vaccination levels among first-grade students at black, Hispanic, and mixed schools were similar (Table 2). However, levels varied substantially among the different cities. For example, 47% of first graders attending predominantly black schools in Jersey City were vaccinated by the second birthday, compared with 79% in Pittsburgh. In two of the three cities with predominantly white schools, first graders in white schools had higher vaccine coverage levels than first graders in other schools.

Overall, in inner-city public schools, the percentage of children vaccinated by the second birthday ranged from 51% in Jersey City to 79% in Pittsburgh. Using data from the first-grade students, an inverse relation was observed between the mean measles incidence during 1980-1989 and measles vaccine coverage levels by the second birthday (Figure 2). Reported by: S Lett, MD, Massachusetts Dept of Health. E Scambio, PhD, New Jersey Dept of Education; K Spitalny, MD, R Ashley, New Jersey Dept of Health. S Friedman, MD, New York City Dept of Health. J Kelly, Cleveland Health Dept; S Young, PhD, TJ Halpin, MD, State Epidemiologist, Ohio Dept of Health. R Levenson, Philadelphia Dept of Health; J Prior, Allegheny County Health Dept, Pittsburgh; R Gens, MD, Pennsylvania Dept of Health. D Freudiger, J Arrandondo, MD, C Buu, MD, Houston Dept of Health, Texas. B Baker, Washington Dept of Health. Div of Immunization, Center for Prevention Svcs, CDC.

Editorial Note

Editorial Note: Although measles vaccination levels are greater than 98% among school-aged children in the United States, levels are lower among preschool-aged children (3). Routine national surveys do not monitor vaccination levels among this age group. Before 1986, data on vaccination levels among preschool-aged children were obtained from the United States Immunization Survey (CDC, unpublished data, 1987) and indicated that 82% of children had been vaccinated by the second birthday. However, this earlier survey provided only aggregate data.

The retrospective surveys described in this report were conducted to explore whether the differences observed in measles incidence rates throughout the 1980s in selected cities were reflected in the measles vaccination levels and to determine the feasibility of conducting more definitive retrospective surveys in selected cities. Such surveys are convenient to perform because school vaccination records can be reviewed easily. However, the data provide a measure of vaccination levels in previous periods. For example, the vaccination levels of the first- and fifth-grade students in 1990 reflect levels among 2-year-old children approximately 4 years (1986) and 8 years (1982) before the surveys, respectively. An additional limitation of this study was the nonsystematic selection criteria of schools in the cities. Therefore, inter-city comparisons of vaccination levels should be interpreted with caution.

Despite these limitations, the race-specific data suggest that measles vaccine coverage is suboptimal among black and Hispanic children, who will be at high risk for measles unless coverage can be improved. In addition, the differing levels of coverage among children in these cities suggest that the success of vaccination programs varies.

Local surveys (2) and data from the nonrandom surveys in this report confirm low vaccination levels in some U.S. cities. However, these surveys indicate that, at least in the schools surveyed, vaccination levels did not decrease during 1982-1986; whether vaccination levels have declined since 1986 is not known. Regardless, levels in the mid-1980s were low enough to sustain measles outbreaks. The reason for the increase in large outbreaks in inner cities in 1989 and 1990 is not known but may have resulted in part from the large increase in measles activity in many neighboring countries in North and Central America (4).

CDC has begun an Infant Immunization Initiative to improve vaccination levels among preschool-aged children in the United States. Effective strategies to vaccinate preschool-aged children are needed to reach national and global objectives for children's health by the year 2000.


  1. CDC. Measles--United States, 1989 and first 20 weeks of 1990. MMWR 1990;39:353-5,361-3.

  2. CDC. Update: measles outbreak--Chicago, 1989. MMWR 1989;39:317-9,325-6.

  3. Orenstein WA, Bernier RH. Surveillance: information for action. Pediatr Clin North Am 1990;37:709-34.

  4. Expanded Program on Immunization in the Americas. Reported cases of EPI diseases. EPI Newsletter 1990;XII(4):7.

    • The definition of inner-city school varied by location.

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