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Epidemiologic Notes and Reports School Immunization Requirements for Measles -- United States, l982

The record low incidence of measles in the United States observed in 1981 (1) resulted from implementation of the measles elimination strategy. The primary component of this strategy is to achieve and maintain a very high percentage of immunity* to measles in the population. Because schools are the primary site of measles transmission in the United States, a major focus of the Measles Elimination Program has been to document that very high percentages of school-age children are vaccinated against measles. The importance of immunizing school-age children is reflected by the fact that in 1980, the most recent year for which age-specific data on measles cases are available, the school-age population 5-19 years old accounted for almost three-fourths (72.1%) of the measles cases (2).

An important means of assuring high immunization levels is enactment and enforcement of school immunization laws. The 2 major categories of school immunization laws are school-entrance laws and comprehensive school-attendance laws. School-entrance laws require documentation of measles immunity at the time of entry into kindergarten or first grade; students already in school when the law goes into effect do not have to comply. School-attendance laws, however, cover all students from kindergarten through grade 12.

In recent years, an increasing number of states have adopted comprehensive school-attendance laws requiring proof of measles immunity for all students from kindergarten through grade 12. In March 1979, only 17 states and the District of Columbia had such comprehensive laws, but by January 1982, this number had increased to 39 states and the District of Columbia (Figure 1). Of the remaining states, 10 have school-entry laws covering only kindergarten and first grade, and 1 has a law covering elementary school only. To ensure that students have been vaccinated with live-measles vaccine on or after their first birthday, most states require that dates of vaccination appear on school records.

Pennsylvania is one of 10 states that lack a comprehensive school immunization law. In the past 2 years, 8 measles outbreaks have occurred in Pennsylvania. In 1980, one such outbreak involved 811 cases in a 6-county area. Of 85,375 students enrolled in schools in these counties, 31,291 (36.7%) lacked adequate evidence of immunity to measles.

Although Pennsylvania comprises only 5% of the U.S. population, 607 (20.0%) of the provisional total of 3,032 measles cases reported in the United States for 1981 occurred in that state. The largest outbreak in the United States in 1981 occurred in Philadelphia, which reported 489 cases to CDC. Approximately 70% of these cases occurred among school-age children (5-19 years). Another large outbreak, in which 156 confirmed cases were reported, occurred in Warren County, Pennsylvania; 86% of the cases were among school-age children. Of 8,315 students enrolled in Warren County schools, 3,210 (38.6%) lacked evidence of adequate immunity to measles. A countywide outbreak-control program was rapidly implemented in this outbreak. Philadelphia is currently engaged in a comprehensive vaccination campaign that involves reviewing the vaccination status of all students enrolled in city schools, holding vaccination clinics, and excluding students from school until they provide adequate evidence of immunity. Comprehensive immunization requirements covering kindergarten through 12th grade are currently being considered in Pennsylvania. Reported by RG Sharrar, MD, Philadelphia, R Gens, MD, Acute Infectious Disease Div, EJ Witte, VMD, MPH, State Epidemiologist, Pennsylvania Dept of Health; Immunization Div, Center for Prevention Svcs, CDC.

Editorial Note

Editorial Note: In recent years, the relationship of low measles incidence to comprehensive school laws has been demonstrated. In 1977 and 1978, low measles incidence was statistically associated with areas having comprehensive school laws that were rigorously enforced by exclusion of susceptible students from school (3). In the 1979-1980 school year, reporting areas in which laws covered all grades had lower measles incidence than did reporting areas in which laws covered only entry into kindergarten or first grade (p = 0.05, Mann Whitney U test) (4).

Vigorous enforcement of school immunization laws is the key to their effectiveness. The most effective means of enforcement is to exclude from school those students who have not provided documented evidence of immunity to measles. Experience with such enforcement programs indicates that necessary vaccinations are quickly obtained by most susceptible pupils and that exclusion from school for significant periods of time is uncommon (5-8).

Continued progress toward eliminating indigenous measles from the United States will be aided considerably if all states have comprehensive immunization laws covering all students. The experience in Pennsylvania indicates that an aggressive surveillance and outbreak-control effort alone cannot interrupt transmission. Enacting and strictly enforcing such comprehensive laws should receive high priority in public health efforts to control or eliminate measles and to maintain the absence of indigenous measles transmission.


l. CDC. Measles--United States, 1981. MMWR 1982;31:37-9. 2. CDC. Age characteristics of measles cases--United States,

1977-1980. MMWR 1981;30:502-3. 3. Robbins KB, Brandling-Bennett AD, Hinman AR. Low measles

incidence: association with enforcement of school immunization laws. Am J Public Health 1981;71:270-4. 4. CDC. School immunization requirements for measles--United States,

l98l. MMWR 1981;30:158-60. 5. Middaugh JP, Zyla LD. Enforcement of school immunization law in

Alaska. JAMA 1978;239:2128-30. 6. CDC. Enforcement of a state's immunization law for entering

school children--Detroit. MMWR 1978;27:7. 7. CDC. Measles and school immunization requirements--United States,

1978. MMWR 1978;27;303-4. 8. CDC. Measles--Florida, 1981. MMWR 1981;30:593-6. *Measles immunity is estimated by either documented physician-diagnosed measles or receipt of live-measles vaccine on or after the first birthday.

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