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From the Centers for Disease Control and Prevention
April 1, 1998

National, State, and Urban Area Vaccination Coverage Levels Among Children Aged 19-35 Months—United States, July 1996-June 1997

JAMA. 1998;279(13):985-986. doi:10.1001/jama.279.13.985

MMWR. 1998;47:108-116

3 tables omitted

The National Immunization Survey (NIS) is an ongoing survey that provides national estimates of vaccination coverage among children aged 19-35 months* based on data for the most recent 12 months for each of the 50 states, the District of Columbia, and 27 other selected urban areas.1,2 CDC initiated the NIS in April 1994 to monitor vaccination coverage levels as part of the Childhood Immunization Initiative (CII), a national strategy to ensure high vaccination coverage of children during the first 2 years of life.3 This report presents NIS findings for July 1996-June 1997, which indicate that vaccination levels among U.S. children aged 19-35 months remain the highest ever recorded. This report also includes the first annualized estimates for varicella vaccine coverage.

NIS uses a quarterly random-digit-dialed sample of telephone numbers for each survey area to collect vaccination information for all eligible children. During July 1996-June 1997, a total of 32,652 household interviews were completed, representing 33,064 children (mean: 424 children per survey area). The overall response rate for eligible households was 67% for all 78 survey areas (range: 55%-83%). For completeness and verification, vaccination data also are requested from vaccination providers. Provider data are weighted to represent the entire group of children surveyed and to account for household nonresponse, natality data, and the lower vaccination coverage levels among children in households without telephones.1,2,4

Compared with 1996, national vaccination coverage with all individual vaccines and the 4:3:1† and 4:3:1:3‡ series during July 1996-June 1997 remained stable at high levels, except that coverage with hepatitis B vaccine showed a small, but statistically significant, increase of 1.5% (from 81.8% to 83.3%).

The national coverage level for varicella vaccine during July 1996-June 1997 was 19%. During the last quarter of this reporting period (April-June 1997), national varicella vaccine coverage was 25%. For July 1996-June 1997, varicella coverage levels ranged from 3% to 33% (median: 17%) among states and from 7% to 33% (median: 16%) among selected urban areas.

During July 1996-June 1997, estimated state-specific coverage levels for the 4:3:1 series ranged from 69% to 91% (median: 79%), and for the 4:3:1:3 series, from 67% to 88% (median: 77%). Estimated coverage levels among selected urban areas ranged from 63% to 86% (median: 77%) for the 4:3:1 series and from 61% to 85% (median: 74%) for the 4:3:1:3 series. Compared with 1996, there were statistically significant changes in state-specific coverage with the 4:3:1:3 series in West Virginia (from 71% to 80%) and New York (from 79% to 74%); among selected urban areas, changes were statistically significant in Marion County, Indiana (from 72% to 78%), and the District of Columbia (from 78% to 72%). During July 1996-June 1997, the coverage range for 4:3:1:3 among the states narrowed compared with 1996 (range: 67%-88% versus 63%-87%, respectively). For urban areas, the 4:3:1:3 coverage range remained virtually unchanged (61%-85% in July 1996-June 1997 versus 62%-84% in 1996).2 (Table 1)

TABLE 1. 
Childhood Immunization Initiative (CII) goals for 1996 and vaccination coverage levels among children aged 19-35 months, by selected vaccines—United States,* National Immunization Survey, July 1996–June 1997†
Childhood Immunization Initiative (CII) goals for 1996 and vaccination coverage levels among children aged 19-35 months, by selected vaccines—United States,* National Immunization Survey, July 1996–June 1997†

Compared with 1996, the number of states and selected urban areas that met the 1996 CII coverage goal for three or more doses of hepatitis B vaccine increased from 48 to 50 and from 27 to 28, respectively. The number that met the goal for three or more doses of DTP increased from 48 to 50 states and decreased from 26 to 25 urban areas; urban areas that did not meet the goal were within 2% below the goal. The number that met the goal for three or more doses of poliovirus vaccine increased from 38 to 40 states and decreased from 17 to 13 urban areas; all remaining states and 13 of the remaining 15 urban areas had coverage levels of 85%-89%. For one or more doses of MCV, the number reaching the 1996 interim coverage goal for measles-mumps-rubella vaccine (MMR) increased from 32 to 37 states, but decreased from 19 to 18 urban areas; all the remaining states and eight of the 10 remaining urban areas had coverage levels of 85%-89%. The number that met the goal for three or more doses of Hib vaccine increased from 41 to 45 states but decreased from 19 to 18 urban areas; all remaining states and nine of the remaining 10 urban areas had coverage levels of 85%-89%. Overall, the number that met all CII vaccination coverage goals, including the goal for hepatitis B vaccine, increased from 30 to 33 states, but decreased from 14 to 11 urban areas.2

Reported by:

National Center for Health Statistics; Assessment Br, Data Management Div, National Immunization Program, CDC.

CDC Editorial Note:

The NIS data in this report indicate that all national coverage goals established by CII for 1996 have been met or exceeded for the vaccines routinely recommended for children. Attainment of these goals reflects the widespread implementation of the comprehensive CII strategy by public- and private-sector organizations and health-care providers at the national, state, and local levels.3

Coverage with hepatitis B vaccine for July 1996-June 1997 increased slightly over 1996 levels, whereas sizable increases occurred from 1994 to 1995 (from 37% to 68%) and from 1995 to 1996 (from 68% to 82%). These findings indicate that substantial effort will be required to attain the 1998 interim national goal of 90% for hepatitis B vaccine.2,3,5

Before the availability of varicella vaccine, approximately 4 million cases occurred each year in the United States, resulting in an annual average of 105 deaths and 4000-9000 hospitalizations. Most cases occur among children and are preventable by vaccination. In 1997, several deaths attributed to varicella among adults were associated with transmission from unvaccinated preschool-aged family members; these deaths underscore the importance of universal childhood vaccination for varicella.6

This reporting period coincided with the first 12 months since the inclusion of varicella vaccine in the recommended childhood immunization schedule in July 1996. The national coverage estimate for varicella vaccine was the lowest of all the recommended vaccines, partially because most children surveyed during this reporting period were aged >18 months before the vaccine was first recommended.2 The wide variation of varicella vaccine coverage by state (from 3% to 33%; median: 16%) indicates a need for special efforts in states with lower coverage levels. The national estimates for the last quarter of this reporting period suggest an upward trend in varicella vaccination coverage. Additional increases are expected with the implementation of the extended financing of varicella vaccination by the Vaccines for Children Program (VFC), which makes available all recommended vaccines to public- and private-sector health-care providers for children who qualify.7 State and local public health officials should encourage more public- and private-sector providers to participate in VFC, which should be especially beneficial for uninsured children and children living below the poverty level.

In this reporting period, the 4:3:1 and 4:3:1:3 series coverage remained relatively unchanged. These findings primarily reflect relatively low coverage with the fourth dose of DTP (81%). On the basis of these data, approximately 1 million children still need one or more of the recommended doses of vaccine to be fully protected.

Although national 1996 CII coverage goals have been attained for all individual vaccines, coverage differed substantially by state and urban area, and many states and urban areas did not meet the 1996 CII goals for the individual vaccines. Moreover, 13 states and 10 urban areas have not achieved the 1995 interim goal for MCV (90%); two urban areas have not achieved the 1995 goal for poliovirus vaccine (85%); and one urban area has not achieved the 1995 goal for Hib vaccine (85%).2 Vaccination providers in these areas should intensify their efforts, so that children are equally well protected throughout the United States.

The addition of new vaccines (e.g., varicella vaccine) to the existing vaccination schedule presents a challenge to the vaccine-delivery system that must be met before the full benefits of new vaccine technology can be realized. The achievement of the 1996 goals during July 1996-June 1997 was a major milestone in the effort to control vaccine-preventable diseases; however, this reporting period indicated only one net gain compared with 1996: a modest increase in hepatitis B vaccine coverage. Furthermore, except for varicella vaccine, no other meaningful increases were detected for the last quarter of this reporting period, which may suggest a leveling off in vaccination coverage. To overcome this apparent leveling in coverage, and to attain the year 2000 objective of 90% coverage with a complete series, vaccination providers must become even more efficient and effective in ensuring full protection of children. Each day, an estimated 11,000 children are born in the United States, and all must receive 12-16 doses of vaccine before the second birthday to be fully vaccinated. Achievement of the 1996 goals demonstrates that reaching high coverage levels is possible but does not ensure such coverage in the future. Meeting these and other goals at the national, state, and local levels requires a fully functional vaccination delivery system, which remains incomplete in 1998. Important components of this system are state- and community-based computerized vaccination registries, which include all children from birth and can identify children in need of vaccines and recall them for missed vaccinations8; ongoing quality assurance and information feedback activities; continuous education programs for parents and health-care providers, which remain to be fully created and implemented9; and expanding and strengthening the links to the Special Supplemental Nutrition Program for Women, Infants, and Children.10 CDC will continue to use NIS to monitor and target efforts to improve vaccination coverage levels in the United States.

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Article Information
*For this reporting period (July 1996-June 1997), the NIS included children born during August 1993-November 1995 (median age: 27 months).
†Four or more doses of diphtheria and tetanus toxoids and pertussis vaccine/diphtheria and tetanus toxoids (DTP/DT), three or more doses of poliovirus vaccine, and one or more doses of measles-containing vaccine (MCV).
‡Four or more doses of DTP/DT, three or more doses of poliovirus vaccine, one or more doses of MCV, and three or more doses of Haemophilus influenzae type b vaccine (Hib).
References
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CDC, Sample design and procedures to produce estimates of vaccination coverage in the National Immunization Survey.  Atlanta US Department of Health and Human Services, CDC1996;
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CDC, Hepatitis B virus: a comprehensive strategy for eliminating transmission in the United States through universal childhood vaccination. MMWR Morb Mortal Wkly Rep. 1991;401- 25
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Shefer  AMaes  EBrink  EMize  JPassino  JP Assessment and related immunization issues in the special supplemental nutrition program for women, infants, and children: a status report. J Public Health Manag Pract. 1996;234- 44Article
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