Factors associated with underimmunization at 3 months of age in four medically underserved areas.
OBJECTIVE
Risk factors for underimmunization at 3 months of age are not well described. This study examines coverage rates and factors associated with under-immunization at 3 months of age in four medically underserved areas.


METHODS
During 1997-1998, cross-sectional household surveys using a two-stage cluster sample design were conducted in four federally designated Health Professional Shortage Areas. Respondents were parents or caregivers of children ages 12-35 months: 847 from northern Manhattan, 843 from Detroit, 771 from San Diego, and 1,091 from rural Colorado. A child was considered up-to-date (UTD) with vaccinations at 3 months of age if documentation of receipt of diphtheria-tetanus-pertussis, polio, haemophilus influenzae type B, and hepatitis B vaccines was obtained from a provider or a hand-held vaccination card, or both.


RESULTS
Household response rates ranged from 79% to 88% across sites. Vaccination coverage levels at 3 months of age varied across sites: 82.4% in northern Manhattan, 70.5% in Detroit, 82.3% in San Diego, and 75.8% in rural Colorado. Among children who were not UTD, the majority (65.7% to 71.5% per site) had missed vaccines due to missed opportunities. Factors associated with not being UTD varied by site and included having public or no insurance, >/=2 children living in the household, and the adult respondent being unmarried. At all sites, vaccination coverage among WIC enrollees was higher than coverage among children eligible for but not enrolled in WIC, but the association between UTD status and WIC enrollment was statistically significant for only one site and marginally significant for two other sites.


CONCLUSIONS
Missed opportunities were a significant barrier to vaccinations, even at this early age. Practice-based strategies to reduce missed opportunities and prenatal WIC enrollment should be focused especially toward those at highest risk of underimmunization.
Immunization Services Division, National Immunization Program, Centers for Disease Control and Prevention, 1600 Clifton Road, MS E-52, Atlanta, GA 30333, USA. bfb7@cdc.gov
Barbara H
BH
Bardenheier
Hussain R
HR
Yusuf
Jorge
J
Rosenthal
Jeanne M
JM
Santoli
Abigail M
AM
Shefer
Donna L
DL
Rickert
Susan Y
SY
Chu
D002140:California; D017028:Caregivers / Q000706:statistics & numerical data*; D016000:Cluster Analysis; D003120:Colorado; D003430:Cross-Sectional Studies; D005191:Family Characteristics; D019538:Health Care Surveys; D006300:Health Services Misuse / Q000706:statistics & numerical data*; D006801:Humans; D017589:Immunization Programs / Q000706:statistics & numerical data*; D007223:Infant; D008499:Medical Records; D008507:Medically Underserved Area; D008824:Michigan; D009519:New York City; D010349:Patient Compliance / Q000208:ethnology / Q000706:statistics & numerical data*; D011203:Poverty; D012307:Risk Factors; D012423:Rural Health / Q000706:statistics & numerical data; D011795:Surveys and Questionnaires; D014481:United States; D014504:Urban Health / Q000706:statistics & numerical data; D014612:Vaccines / Q000008:administration & dosage* / Q000145:classification
D014612:Vaccines