1. 19 to 35 Month Old Children Who Are One Dose Short of Series Completion
Natalie Darling, M.P.H.
Kate Shaw, M.S.
Lawrence Barker, Ph.D
National Immunization Program
Centers for Disease Control and Prevention

2. Background
Immunization coverage is determined by the number of fully vaccinated children
Children must complete the 4:3:1:3:3† series to be fully protected
† 4+ doses of diphtheria and tetanus toxoids and pertussis vaccine, or diphtheria and tetanus toxoids [DTP/DTaP/DT], 3+ doses of poliovirus vaccine, 1+ doses of MCV, 3+ doses of Haemophilus influenzae type b vaccine and 3+ doses of hepatitis B vaccine
Start off with a summary, so the audience will see where we are heading

3. Background, continued
Children who are not fully immunized may be just 1 dose from series completion
2002 coverage, 75% of U.S. children aged months were fully immunized for 4:3:1:3:3
25% were not fully immunized
10% were missing just 1 dose
Start off with a summary, so the audience will see where we are heading

4. Background, continued
If the children missing 1 dose had been fully immunized, national coverage would have been 85% in 2002
State registries
Start off with a summary, so the audience will see where we are heading

5. Introduction
Demographic factors are associated with immunization coverage (e.g., race/ethnicity, sex, poverty level, etc…)
If missing 1 dose is associated with demographic factors, these demographics may be used to target interventions

6. Objective
To determine whether demographics are associated with being 1 dose from series completion among month old children

7. Survey Instrument: The National Immunization Survey (NIS)
The NIS is a random-digit dialing survey that measures vaccination coverage of U.S. children 19 to 35 months old
covers 78 Immunization Action Plan areas
conducted quarterly
date of household interview
provider-verified data

8. Target Population

9. Target Population, continued
Target Population: Children 19 to 35 months old who are not series complete (25% in 2002)

10. Methods
Bivariate comparisons of demographics among children 1 dose and > 1 doses short from series completion
■ Race/ethnicity ■ Gender
■ Age group ■ Birth order
■ Foreign-born ■ Provider
■ Marital status ■ Maternal education
■ Census region ■ Geographic mobility
■ Metropolitan area ■ Income-poverty level
■ Children in household

11. Methods, continued Compared demographics using Chi-square test
Since 58% of series incomplete children were missing a dose of DTaP, we repeated the analysis using 3:3:1:3:3†
†same as 4:3:1:3:3, but with 3 doses of DTP/DTaP/DT

12. Results
Geographic mobility† was significant among children missing 1 and > 1 doses of 4:3:1:3:3
42% of non-mobile children were just 1 dose from series completion compared to 33% of mobile children (p-value = 0.01)
†Mobile children represented 3% of 2002 NIS

13. Results, continued
When we repeated our analysis using 3:3:1:3:3, foreign-born† status was significant
41% of non foreign-born children were just 1 dose from series completion compared to 24% of foreign-born (p-value = 0.04)
†Foreign-born children represented <1% of 2002 NIS

14. Results, continued
For the remaining demographics that we measured, we found no significant differences between groups

15. Conclusion
From our analysis, geographic mobility was the only significant finding among the 4:3:1:3:3 series incomplete children
Foreign-born status was significant for repeated analysis using 3:3:1:3:3
Demographics collected in the NIS may not be useful for identifying children within 1 dose of series completion

16. Strengths and Limitations
National sample
Statistical adjustments
Weighted data
Large sample size
N=5128 children
Limitations
Adjustments not perfect
Random digit-dialing sample might not fully represent U.S. population

17. Future Analysis Additional methods for data collection
Parental knowledge, beliefs and attitudes
Analyses are ongoing
Our findings may provide a springboard for other research in identifying under-immunized children