1. Immunization Disparities in U. S
Immunization Disparities in U.S. Cities: Does Coverage Vary in Proportion to the Demographic Characteristics of Urban Areas?
Karen Wooten, MA; Qian Li; James Singleton, MS National Centers for Disease Control and Prevention National Immunization Program
I will present preliminary results of an investigation of Immunization disparities in U.S. cities. My coauthors are Qian Li and Jim Singleton, also with the Immunization program. Because disparities in Immunization vary significantly across urban areas of the United States, we questioned whether the demographic characteristics of urban areas could play a role in the level of coverage reported for a given area.

2. Background
Differentials in morbidity and mortality may be due to characteristics of places where people live.
Vaccination Coverage varies significantly by urban area
Recent studies have shown that at least a portion of morbidity and mortality differentials may be due to the characteristics of the places where people live and, because vaccination coverage levels vary significantly across states, counties, and urban areas, urban characteristics such as rates of employment, proportion of households living below poverty, for example, may be the pathways through which vaccination coverage levels vary across urban areas.

3. Purpose of Study
Examine the association between demographic conditions of urban areas and vaccination coverage
What urban characteristics are associated with disparities in vaccination coverage levels?
The purpose of this study was to examine associations between demographic characteristics of urban areas and vaccination coverage, and determine which urban characteristics are likely to have the greatest impact on immunization disparities.

4. 28 Urban Areas Baltimore, MD Bexar Co., TX Boston, MA Chicago, IL
Cuyahoga Co., OH
Dade Co., FL
Dallas Co., TX
Davidson Co., TN
Detroit, MI
Duval Co., FL
El Paso Co., TX
Franklin Co., OH
Fulton/Dekalb Co., GA
Houston, TX
Jefferson Co., AL
King Co., WA
Los Angeles Co., CA
Maricopa Co., AZ
Marion Co., IL
Milwaukee Co., WI
Newark, NJ
New Orleans, LA
New York City, NY
Philadelphia, PA
San Diego Co., CA
Santa Clara Co., CA
Shelby Co., TN
Washington DC
For each of THESE 28 urban areas, we examined vaccination coverage levels and area level characteristics.

5. Methods 2003-2004, National Immunization Survey (NIS)
Children between 19 and 35 months of age
Random Digit Dialed (RDD) Telephone Survey
Weighted for national representation of children 19 to 35 months of age
Only children with provider-reported vaccination histories were included in the analysis
2000 Census (Factfinder.census.gov)
Urban Level social indicators
We used two data sources for this study, the National Immunization Survey and the 2000 U.S. Census. The NIS is a random digit dialed telephone survey of age-eligible households in the 50 states and 28 selected urban areas. The 28 urban areas were initially selected in 1994 for oversampling minority populations and remained a part of the NIS sampling design through ONLY children with provider-reported vaccination histories were included in the study. The data are weighted to account for the probability of selection and non-sampling error and represent a national sample of children 19 to 35 months of age. We combined the survey data because of sample size concerns in generating stable coverage levels for the 28 urban areas,. Area level attributes were taken from the Census Bureau’s American Fact Finder Website of the 2000 census and combined with vaccination coverage levels.

6. Analytic Methods
Urban area vaccination levels calculated using SUDAAN Software Package
Survey analysis tool for complex sample survey data
Urban area characteristics from Census 2000 were combined with vaccination levels from NIS :
SAS Software to:
Compute correlation coefficients, significant at P <0.05
Rank order urban areas by area characteristics
Coverage levels were estimated using the SUDAAN software package which takes into consideration the complex sample survey design of the NIS. We used the Statistical Analysis Software system to compute correlation coefficients and rank order urban areas by area characteristics. Statistical significance was based on correlation coefficients with p values less 0.05.

7. Outcome Measures
Vaccination Coverage is based on the percentage of children up-to-date for the 4:3:1:3:3 series:
4+ doses of Diphtheria and Tetanus toxoids and pertussis vaccine
3+ doses of any poliovirus vaccine
1+ doses of measles-containing vaccine
3+ doses of Haemophilus Influenzae type B vaccine
3+ doses of Hepatitis B vaccine
Racial Disparity within urban areas:
Coverage rate differences among race/ethnic groups
We used two outcome measures for this investigation: Vaccination coverage and racial disparity. Vaccination coverage was based on the percentage of children up-to-date for the 4:3:1:3:3 vaccine series and includes the five vaccines listed here.
Racial disparity for each of the 28 urban areas was based on the absolute difference in coverage levels between the race/ethnic group with the highest coverage and the race/ethnic group with the lowest coverage for a given urban area. The percentage point difference between the two estimates were used as a measure of racial disparity for the area.

8. 25 area level indicators Median household income Per capita income
Children and families living below poverty
Higher education attainment
Married population
White population
Households with children (<5years, < 18 years)
Black and Hispanic Population
Foreign Born Status
Other language spoken at home
Ancestry
Grandparents as caregivers
Median Age
Movement from different county
Movement within same county
Movement from different state
Diversity Index
Population Density
Homeownership
Labor Market participation
Unemployment
Vacant housing units
We selected these twenty-five area level characteristics for comparison. Correlation analysis identified 10 of these to be significantly correlated with vaccination coverage across the 28 urban areas and are highlighted in yellow. These include median household income and per capita income, families and children living below poverty, race/ethnicity and ancestry, households with children, and median population age.

9. Urban Areas with the lowest vaccination coverage rates:
Houston, TX (67.4%)
Detroit, MI (68.7%)
Dallas Co., TX (69.4%)
El Paso Co., TX (71.0%)
New Orleans, LA (72.4%)
Vaccination coverage ranged from a low of 67.4% in Houston TX to a high of 85.6% in Boston, MA. The five areas listed here are those reporting the lowest vaccination coverage among the 28 urban areas. These five areas were more likely to have lower per capital income, below the norm for median household income, have a larger proportion of families living below poverty, and a larger percent of children under 5 years of age compared to the five areas with the highest coverage levels.

10. Urban Areas with the highest vaccination coverage rates:
Dade Co., FL (82.7%)
Santa Clara Co., CA (84.1%)
Franklin Co., OH (84.1%)
Davidson Co., TN (84.6%)
Boston, MA (85.6%)
These five urban areas reported the highest vaccination coverage among the 28 urban areas examined. These were more likely to have above average per capital income, above average education attainment, an older population, and have a smaller percentage of families with children living below poverty. The next five slides will describe the relationship between these 4 urban characteristics and vaccination coverage levels for the 28 urban areas.

11. Per capita income Santa Clara Co., CA King Co., WA Boston, MA
Houston, TX
Dade Co., FL
Detroit, MI
As Per Capita income increased by urban areas, vaccination coverage also increased. Houston TX and Detroit Michigan were among the urban areas with the lowest per capita income, and also among those with the lowest vaccination coverage levels.

12. Percent of adult population with college degree or higher
Santa Clara Co., CA
Houston, TX
Boston, MA
Detroit, MI
As the size of the adult population with a college degree or higher increased, vaccination coverage levels also increased. Houston had a low percent of adults with a college degree and also had the lowest vaccination coverage compared to Santa Clara Co. CA and Boston MA. These areas reported the highest vaccination coverage levels and also had a higher percentage of adults with a college degree or more.
Newark, NJ

13. Median age Davidson Co., TN Houston, TX Detroit, MI Boston, MA
As the median age of urban areas increased, vaccination coverage levels generally increased. Houston and Detroit had the lowest vaccination coverage and were also listed among the areas as having the youngest population.

14. Percent of families with children under 5 years living in poverty
New Orleans, LA
Detroit, MI
Newark, NJ
Houston, TX
Boston, MA
Franklin Co., OH
As the percent of families with children under 5 years of age decreased, vaccination coverage increased. Detroit MI and Houston, TX had larger proportions of families living below poverty, and the lowest vaccination coverage. Franklin Co. OH and Santa Clara Co., CA had fewer families living below poverty and also among the areas with the highest vaccination coverage.
Santa Clara CO., CA

15. Results: Disparity In Vaccination Coverage
Excludes:
Dade Co., FL
Duval Co., FL
Cuyahoga Co., OH
Franklin Co., OH
Houston, TX
Dallas, TX
El Paso Co., TX
Los Angeles Co., CA
Significant characteristics:
Families living below poverty
Children living below poverty
Families w/children <5 years living below poverty
white population
Black population
Married couple population
The next set of slides examine racial disparity in coverage rates across 20 of the 28 urban areas. We removed eight areas because of insufficient samples for racial/ethnic comparisons. The measurement for racial disparity is based on the absolute difference in coverage between the race/ethnic group with the highest coverage and the race/ethnic group with the lowest coverage for a given urban area. 0f the 25 urban characteristics examined, 6 were statistically correlated with racial disparity. These included percent of families living in poverty, percent of children living below poverty, percent of families with children under 5 years of age living below poverty, percent white population, percent black population, and percent married couple population.

16. Urban areas with the least racial disparity in vaccination coverage:
Chicago, IL (76.9%)
Baltimore, MD (80.0%)
Marion Co., IN (76.7%)
Boston, MA (85.6%)
Santa Clara Co., CA (84.1%)
These 5 urban areas reported the least racial disparity in vaccination coverage, with Chicago reporting a <2 percentage points difference in coverage and Santa Clara Co, CA reporting less than 4 percentage points difference in coverage.

17. Urban areas with the greatest disparity in vaccination coverage
Washington, DC (79.3%)
Philadelphia, PA (77.6%)
Fulton/Dekalb Co., GA (80.4%)
Detroit, MI (68.7%)
New Orleans, LA (72.4%)
These 5 urban areas reported the largest racial disparity in vaccination coverage, with Fulton/Dekalb Co., GA, Detroit, MI, and New Orleans, LA reporting larger than a 15 percentage point difference in coverage between racial/ethnic groups. These were more likely to have a larger proportion of children under 5 years of age living below poverty, a smaller white population, a smaller married couple population, and a larger black population. The next four slides will describe the relationship between these four characteristics and racial disparity.

18. Racial disparity in coverage by percent white population in urban areas
New Orleans, LA
Fulton/Dekalb CO., GA
Detroit, MI
Maricopa Co., AZ
This graph describes the correlation between racial disparity in coverage and size of the white population per urban area. As the size of the white population increased, racial disparity in vaccination coverage decreased.
Baltimore, MD

19. Racial disparity in coverage by percent black population in urban areas
New Orleans, LA
Detroit, MI
Bexar Co., TX
Washington DC
Jefferson Co., AL
The opposite is shown for size of the black population. As the size of the black population increased, racial disparity in vaccination coverage also tended to increase.
Chicago, IL
Santa Cara Co., CA

20. Racial disparity in coverage by size of married couple population
New Orleans, LA
Detroit, MI
King Co., WA
Baltimore, MD
Santa Clara CO., CA
This graph describes the correlation between racial disparity in coverage and size of the married couple population per urban area. As the size of the married couple population increased, racial disparity in coverage decreased.

21. Racial Disparity by Percent of families with children <5 years of age living below poverty
This last scatter plot depicts the correlation between racial disparity in coverage and the percent of families with children less than 5 years of age living below poverty. As the proportion of families with small children living in poverty increased, racial disparity in coverage increased.

22. Limitations
Some vaccination providers not identified, did not respond, or did not return a complete report; incomplete medical records may result in underreporting
Vaccination coverage was not controlled for individual level factors.
Census figures for 2000 may not be representative of populations in
A few limitations need to be mentioned before summary comments are made. The NIS relies on identification of vaccination providers by the household respondent and complete and accurate reporting of vaccination histories by the immunization providers. Some providers were either not identified, did not respond to the survey, or did not report complete vaccination histories. Incomplete medical records may result in underreporting of the 4:3:1:3:3 series completion.
Coverage levels reported per urban area were not adjusted for differences at the individual level and were assumed to be representative of area level coverage. It is unclear how much of the variations in urban area coverage is due to individual level differences. Additional analysis will include these adjustments.
The 2000 Census figures may not be representative of the selected urban populations in , more recent area level information may be needed.

23. Summary
Vaccination coverage may be a function of urban characteristics:
Urban areas with greater social deprivation such as lower education, low per capita income had the lowest vaccination coverage levels while areas with less deprivation had the highest vaccination coverage levels.
Urban characteristics may be useful in predicting racial disparity in immunization.
Vaccination coverage may be a function of urban characteristics. Urban areas with greater social deprivation such as lower education, low per capita income had the LOWEST vaccination coverage levels while areas with less deprivation had the HIGHEST vaccination coverage levels. This analysis may offer possible explanations for low vaccination coverage levels and racial/ethnic disparity in some urban areas. Differentials across urban areas may be contributing factors.
Our results suggest the possibility of an economic burden to urban areas with a large child population and an above average numbers of families living below poverty.

24. Conclusion
As general social and economic wellbeing at the macro level improves, vaccination coverage levels are also likely to improve.
Our findings suggest that the need for more research that investigates the influence of urban characteristics on vaccination coverage levels and racial disparities.
This study may offer possible reasons why vaccination levels are lower in some areas, and why racial/ethnic disparity is greater in other areas. As general social and economic wellbeing at the macro level improves, vaccination coverage levels are also likely to improve and racial disparities are likely to be reduced. Our findings suggest that the need for more research that investigates the influence of urban characteristics on health, and particularly immunization.

25. Contact Information
Karen Wooten, MA
Health Scientist
Centers for Disease Control and Prevention
National Immunization Program
Immunization Services Division
1600 Clifton Road E62
Atlanta, GA 30329