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

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

Background, continued Children who are not fully immunized may be just 1 dose from series completion 2002 coverage, 75% of U.S. children aged 19-35 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

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

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

Objective To determine whether demographics are associated with being 1 dose from series completion among 19-35 month old children

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

Target Population

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

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

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

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

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

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

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

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

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