1. Enrique Ramirez1, Julie Morita1
Estimating Community-Level Immunization Coverage Rates Using Public School Immunization Data and CASA*
Enrique Ramirez1, Julie Morita1
Chicago Department of Public Health, Immunization Program
* Clinic Assessment Software Application (CASA)

2. Background
Childhood immunization rates are among the indicators used in Healthy People 2010 to assess the health of the nation
Vaccination coverage objective: Achieve and maintain effective (90%) immunization coverage levels for universally recommended vaccines among young children
* U.S. Department of Health & Human Services. Healthy People 2010.

3. MMR Coverage Rates Among 19-35 month olds, National Immunization Survey (NIS), 2001
U.S.(%)
Chicago(%)
Total Population
91.4
87.4
Non-Hispanic White
91.7
93.6
Non-Hispanic Black
89.1
82.9
Hispanic
92.1
88.0
CDC. National, state, and urban area vaccination coverage levels among months
– United States, MMWR.2002;51:664-66

4. Chicago Total population: 2.9 million
Population < 3 years: 131,478*
Area of Chicago: square miles
Community Areas: 77
Many racially, ethnically, and socio-economically segregated
* 2000 US Census

5. Community-Level Immunization Coverage Rates Needed
To identify communities with low immunization coverage rates
To direct resources to communities with low immunization coverage rates
Household surveys too expensive and labor intensive to do in all 77 communities
Less expensive and more efficient method needed

6. Study Objectives
Determine city and community immunization coverage rates among kindergarteners at 35 months of age using immunization records stored in the Chicago Public Schools (CPS) “health database”
Compare coverage rates determined with Public School Immunization Data (PSID) to other estimates determined using standard methods (i.e., NIS, household survey, manual record review)

7. Public School Immunization Data
CPS provided Chicago Department of Public Health (CDPH) with PSID for kindergarteners entering school from 2000 through 2003
Fixed-format text files containing:
Demographic information – race, gender, date of birth
Required immunization dates
Home address

8. Determining Immunization Coverage Rates
SAS
Format data for CASA
CASA
Calculate immunization coverage rates
SPSS
ANOVA - test for racial differences in immunization coverage
Intelligent Dispatcher & GIS
Geographic coding

9. Kindergartener Population* CPS, 2000-2003
Children 4-7 years of age with complete home address
Total number: 131,044
Racial Breakdown: Gender Breakdown:
White: 9% -Female: 49%
Black: 46% -Male: %
Hispanic: 42%
Other: 3%
*aggregated across all 4 years

10. Percentage of 5 year olds included in PSID Database, by Race, 2000
2000 US Census
2000 PSID Database %
TOTAL
44,964
32,012
71%
White
6,524
2,973
46%
Black
19,962
14,767
74%
Hispanic
16,276
13,278
82%

11. MMR Coverage Rates Among 35 month olds by Race, PSID for 1997-2000† *
Total population White Black Hispanic
*p < with White as referent group
†p=0.61 with White as referent group

12. among CPS Kindergarteners at 35 months by Community Area 1997-2000
Average MMR Coverage
among CPS Kindergarteners at
35 months by Community Area
90% and above
(Healthy People 2010 Objective) %
(above 80% to prevent epidemic transmission)
Below 80%
Consistently Below 80% from

13. MMR Coverage Among 35 month olds, PSID vs. NIS, 2000
Vaccine
Source
Total
White
Black
Hispanic
1 MMR
PSID
84.56
89.53
79.03
89.46
NIS

14. MMR Coverage Among 35 month olds, PSID vs. Record Review, 2003
School
PSID Database
Immunization Records*
School 1
80%
84% (+13.8)
School 2
89%
88% (+11.9)
School 3
81%
78% (+4.1)
School 4
84% (+12.2)
School 5
84%
92% (+15.8)
School 6
79%
72% (+7.1)
*Schools and immunization records randomly selected. Immunization
records manually entered into CASA.

15. MMR Coverage Among 35 month olds, PSID vs. Cluster Survey, 2000
Cluster survey in one community area conducted in 2000 *
Reported MMR coverage among 35 month old children: 74% (n=145)
MMR coverage rates among 35 month olds using PSID for the same community: 71.9% (n=695)
* Rosenthal J, Raymond D, Morita J, et al. African-American children are at risk of a measles outbreak in an inner-city community in Chicago,2000.Am J Prev Med; 2002;23:

16. Conclusions
PSID & CASA can be used to determine city, community and school estimates of immunization coverage rates for 35 month olds
PSID estimates of immunization coverage rates were similar to estimates from NIS, school record review and a community cluster survey
PSID confirmed that immunization rates are low and that racial disparities exist in Chicago
PSID can be used to identify pockets of under-immunization in Chicago

17. Limitations
PSID cannot be used to determine current immunization coverage rates
Estimates from PSID may underestimate true immunization coverage since CPS students likely have lower socioeconomic status than the general population

18. Recommendations
Resources to support implementation of interventions should be directed to the 12 under-immunized communities in Chicago
CDPH should continue to utilize PSID to monitor immunization rates in Chicago communities
Other states or cities interested in identifying poorly immunized subpopulations should consider using CASA to analyze school immunization data