The goals of the Childhood Immunization Initiative (CII) for 1996 were to have greater than or equal to 90% of children receive three or more doses of diphtheria and tetanus toxoids and pertussis vaccine/diphtheria and tetanus toxoids (DTP/DT), poliovirus vaccine, and Haemophilus influenzae type b vaccine (Hib) and one dose of measles-mumps-rubella vaccine, and for greater than or equal to 70% of children to receive three or more doses of hepatitis B vaccine (1). The National Immunization Survey (NIS) was undertaken as part of the CII to monitor vaccination coverage levels for each state and for 28 urban areas (2). This report presents coverage estimates by race/ethnicity and poverty level for 1997 and compares coverage estimates for 1995 and 1997; the findings indicate improvements in vaccination coverage levels among children living below poverty level * although these levels were lower than levels among children living at or above poverty level.

Each quarter since April 1994, an independent random sample of telephone numbers has been selected using random-digit dialing in the 78 survey areas to collect vaccination information for all children aged 19-35 months. With the consent of parents, vaccination data are verified with the children's health-care providers. NIS data are weighted to represent all children surveyed and to account for household non-response and lack of telephone coverage. Demographic characteristics and reported vaccination coverage of children with and without provider information were similar (2). In 1997, information on 32,742 children was collected from parents; provider information was collected for 22,393 (68.4%) of these. Of children with provider data, 66% were non-Hispanic white, 15% were non-Hispanic black, 14% were Hispanic, 1% were American Indian/Alaskan Native, 3% were Asian/Pacific Islander, and 1% were of other or unknown race/ethnicity.

Overall, vaccination coverage levels for the 22,393 children surveyed met or exceeded CII goals: coverage for three doses of DTP (DTP3) ranged from 92% among American Indians/Alaskan Natives to 97% among non-Hispanic whites; for three doses of poliovirus vaccine, the range was from 88% among Asians/Pacific Islanders to 92% among non-Hispanic whites; for Hib, the range was from 87% among American Indians/Alaskan Natives to 94% among non-Hispanic whites; for measles-containing vaccine (MCV), the range was from 88% among Hispanics to 92% among non-Hispanic whites; and for hepatitis B vaccine, the range was from 81% among Hispanics to 88% among Asians/Pacific Islanders. All racial/ethnic groups achieved the CII hepatitis B vaccine goal. Although a few racial/ethnic groups had point estimates less than 90% for vaccines covered by CII goals other than hepatitis B, the 95% confidence interval overlapped the CII goal with the exception for coverage with MCV among Hispanics (Table_1).

Coverage levels were low for the fourth dose of DTP (DTP4), ranging from 77% among Hispanics to 84% among non-Hispanic whites. The low coverage for DTP4 was the major contributor to low vaccination levels for the combined series, which were substantially lower than coverage for individual vaccines (Table_1).

Compared with children living at or above poverty level, children living below poverty level had significantly lower coverage for all vaccines. Coverage for DTP3 for children living below poverty level compared with coverage for children living above poverty level was 93% and 97%, respectively (pless than 0.03); for polio, coverage was 90% and 92%, respectively (pless than 0.05); for Hib, coverage was 90% and 94%, respectively (pless than 0.03); for MCV, coverage was 86% and 92%, respectively, (pless than 0.03); and for hepatitis B vaccine, coverage was 80% and 85% (pless than 0.03), respectively.

Among children living below poverty level, few statistically significant differences in coverage by race/ethnicity were observed: Asian/Pacific Islander children had higher coverage with hepatitis B vaccine and with DTP4 than non-Hispanic white, non-Hispanic black, and Hispanic children. Non-Hispanic black children had higher coverage with DTP3 than Hispanic children.

Since 1995, the differences between the racial/ethnic groups with highest and lowest coverage levels has not changed substantially except for hepatitis B vaccine. For coverage with DTP4, poliovirus vaccine, and MCV, the gap between highest and lowest coverage levels in 1997 compared with 1995 decreased two, one, and five percentage points, respectively; however, differences in coverage for DTP3 and Hib increased two and three percentage points, respectively. In contrast, the gap was narrowed substantially for hepatitis B vaccine; differences between highest and lowest coverage levels by racial/ethnic group was 25 percentage points in 1995 (3), and in 1997, this difference was reduced to seven percentage points. Improvements have occurred in hepatitis B vaccine coverage among all racial/ethnic groups, with increases between eight and 28 percentage points between the 1995 (3) and the 1997 NIS. Coverage with hepatitis B vaccine was highest in 1997 among Asian/Pacific Islander children.

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

Editorial Note

Editorial Note: In 1997, the NIS documented substantial progress in increasing vaccination levels among children living below poverty level; however, vaccine coverage levels remained lower than levels among children living at or above poverty level. Coverage levels for several vaccines were higher in 1997 than in 1995 among children living below poverty level in each racial/ethnic group except Asians/Pacific Islanders. Although coverage levels for Asian/Pacific Islander children living below poverty level did not improve, the lower precision of estimates among children in this group may mask any improvements.

Differences in coverage levels among racial/ethnic groups partly are accounted for by poverty level. In 1996, approximately 14.5 million children lived below poverty level; more than two thirds of black children and approximately three quarters of Hispanic children were living below or near poverty level (3). Studies are needed to determine how poverty is associated with undervaccination to target interventions and improve coverage.

The goals of the CII are to 1) eliminate indigenous cases of six vaccine-preventable diseases; 2) increase vaccination coverage; and 3) establish a vaccination delivery system that maintains and improves high vaccination coverage (1). The framework for meeting the CII goals include improving the quality and quantity of vaccination delivery services, increasing community participation and education, reducing the cost of vaccines for parents, improving surveillance for coverage and disease, forming and strengthening partnerships, and improving vaccines (1). Efforts that may have contributed to improvements in vaccine coverage among children living below poverty level include the Vaccines for Children Program (4); federal support of state assessment and provider feedback of coverage levels in public clinics and community and migrant health centers (5); and strong linkages with the Special Supplemental Nutrition Program for Women, Infants, and Children (6). Efforts such as these are needed to maintain high levels of coverage where they exist and to reduce differences in coverage levels by race/ethnicity, poverty level, and other factors associated with undervaccination.

References

1. CDC. Reported vaccine-preventable diseases -- United States, 1993, and the Childhood Immunization Initiative. MMWR 1994;43:57-60.

2. CDC. Sample design and procedures to produce estimates of vaccination coverage in the National Immunization Survey. Atlanta, Georgia: US Department of Health and Human Services, Public Health Service, CDC, National Immunization Program, April 18, 1996.

3. National Center for Health Statistics. Health, United States, 1998, with socioeconomic status and health chartbook. Hyattsville, Maryland: US Department of Health and Human Services, CDC, National Center for Health Statistics, 1998.

4. Zimmerman RK, Medsger AR, Ricci EM, et al. The impact of free vaccine and insurance status on physician referral of children to public vaccination clinics. JAMA 1997;278:996-1000.

5. CDC. Recommendations of the Advisory committee on Immunization Practices: programmatic strategies to increase vaccination rates -- assessment and feedback of provider-based vaccination coverage information. MMWR 1996;45:219-20.

6. Hoekstra EJ, LeBaron CW, Megaloeconomou Y, et al. Impact of a large-scale immunization initiative in a special supplemental nutrition program for women, infants, and children (WIC). JAMA 1998;280:1143-7.

Poverty status is based on family income and household size using Bureau of the Census poverty thresholds for 1997. Children for whom poverty level was not determined were excluded from this analysis.

TABLE 1. Vaccination coverage levels for selected vaccines among children aged 19-35 months living below poverty level*
and all children, by race/ethnicity+ -- United States, National Immunization Survey, 1997&
=====================================================================================================================================================================================================================
                                                                                                                                                   American Indian/
                               Non-Hispanic white                     Non-Hispanic black                          Hispanic                          Alaskan Native                   Asian/Pacific Islander
                           -----------------------------        ------------------------------          -----------------------------       ------------------------------       ------------------------------
                              Below          Total              Below             Total                Below             Total                  Below             Total              Below             Total
                          -------------      -----------        -------------      -----------          -----------       -----------       ------------      ------------        -----------       -----------
Vaccine/Dose              %   95% CI@        %   95% CI         %    95% CI       %   95% CI           %   95% CI        %   95% CI         %    95% CI       %    95% CI         %   95% CI        %   95% CI
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
DTP/DT**
 >=3 doses                93    +/-1.3       97   +/-0.3        95    +/-1.3      95   +/-0.8          92   +/-1.6       93   +/-0.9        92    +/-5.3      92    +/-3.2        96   +/-3.4       95   +/-1.5
 >=4 doses                76    +/-2.2       84   +/-0.6        76    +/-2.5      78   +/-1.4          75   +/-2.6       77   +/-1.5        79    +/-8.3      80    +/-4.6        86   +/-6.5       80   +/-2.9
Poliovirus
 >=3 doses                90    +/-1.5       92   +/-0.5        90    +/-1.8      90   +/-1.1          89   +/-1.9       90   +/-1.1        93    +/-5.1      91    +/-3.4        89   +/-5.4       88   +/-2.4
Haemophilus
 influenzae type b
 (Hib)
 >=3 doses                90    +/-1.5       94   +/-0.4        92    +/-1.6      92   +/-0.9          89   +/-1.9       90   +/-1.1        93    +/-5.2      87    +/-4.0        85   +/-6.3       89   +/-2.3
Measles-containing
 vaccine (MCV)++
 >=1 doses                85    +/-1.8       92   +/-0.5        88    +/-1.9      90   +/-1.1          88   +/-1.9       88   +/-1.2        92    +/-5.4      92    +/-3.1        91   +/-5.0       89   +/-2.2
Hepatitis B
 >=3 doses                80    +/-2.0       85   +/-0.6        82    +/-2.2      83   +/-1.3          79   +/-2.5       81   +/-1.4        83    +/-7.4      83    +/-4.3        94   +/-4.4       88   +/-2.4
Combined series
 4 DTP/3 Polio/
   1 MCV                  73    +/-2.2       80   +/-0.7        72    +/-2.6      74   +/-1.5          72   +/-2.7       74   +/-1.6        78    +/-8.3      78    +/-4.8        82   +/-7.0       75   +/-3.1
 4 DTP/3 Polio/
   1 MCV/3 Hib            72    +/-2.3       79   +/-0.7        71    +/-2.6      73   +/-1.5          70   +/-2.8       72   +/-1.6        78    +/-8.4      72    +/-5.1        73   +/-8.0       70   +/-3.3
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
*  Poverty status is based on family income and household size using Bureau of the Census poverty thresholds for 1997. Children for whom poverty level
   was not determined were excluded from this analysis.
+  The race groups non-Hispanic white, non-Hispanic black, American Indian/Alaskan Native, and Asian/Pacific Islander do not include children of
   Hispanic origin. Children of Hispanic origin may be of any race.
&  Children studied were born during February 1994-May 1996.
@  Confidence interval.
** Diphtheria and tetanus toxoids and pertussis vaccine/diphtheria and tetanus toxoids.
++ Childhood Immunization Initiative goals are for measles-mumps-rubella vaccine; estimates are for MCV.
=====================================================================================================================================================================================================================

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