Extraimmunization in children through 2000.
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Biomedical subjects
Publications and source records attributed to Susan Y Chu.
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OBJECTIVE: To compare coverage estimates of foreign-born children 19 to 35 months old with those of US-born children of the same age group. METHODS: The National Immunization Survey is a multistage, random-digit dialing survey designed to measure vaccination coverage estimates of US children 19 to 35 months old. Data from 1999-2000 were combined to permit comparison of vaccination coverage among foreign- and US-born children. RESULTS: Foreign-born and US-born children 19 to 35 months of age had comparable 3:3:1 series coverage (3 or more doses of diphtheria and tetanus toxoids and pertussis vaccine [DTP/DTaP/DT], 3 or more doses of poliovirus vaccine, and 1 or more doses of measles-containing vaccine), the standard in most countries. However, coverage for a US standard, 4:3:1:3 series (4 or more doses of DTP/DTaP/DT, 3 or more doses of poliovirus vaccine, 1 or more doses of measles-containing vaccine, and an adequate number of Haemophilus influenzae type b [Hib] doses based on age at first dose) was lower among foreign-born children because of markedly lower Hib cover and marginally lower DTP/DTaP/DT coverage. In addition, hepatitis B coverage was markedly lower in foreign-born children. CONCLUSION: Lower vaccination coverage among foreign-born children, especially against Hib and hepatitis B, is of concern because foreign-born children often live in households and communities characterized by more intense exposure to these diseases, and many originate from countries with much higher prevalence rates of these diseases than the United States. The differences in Hib and hepatitis B coverage suggest a need for increased culturally competent public health immunization interventions to increase coverage among foreign-born children.
OBJECTIVE: To examine the timeliness of vaccine administration among infants and young children in the United States. METHODS: We analyzed age at receipt of vaccines among 16 211 children aged 24 to 35 months in the 2000 National Immunization Survey and examined receipt at the recommended time of each dose and selected vaccination series, as well as receipt at 4 additional time frames: acceptably early, late, never by 24 months, and too early to be considered valid. We also examined the relationship between timeliness of vaccinations and characteristics of the child, mother, and immunization provider, using multivariate logistic regression. RESULTS: Only 9% of children received all recommended vaccines at the recommended ages. The rates varied significantly by antigen, ranging from 24% for all Haemophilus influenzae type b doses to 75% for all hepatitis B doses as recommended. Overall, 55% of children did not receive all recommended doses by 24 months of age, and 8% of children received at least 1 vaccination dose too early to be considered valid. Factors associated with not receiving all vaccines as recommended were having more children in the household, mothers younger than 30 years, use of public providers, and multiple vaccination providers. CONCLUSIONS: By 24 months of age, 9 of 10 children received at least 1 vaccine outside the recommended age ranges. High vaccination status of children at 24 months of age does not reflect the reality that many vaccinations are not given at the appropriate ages. Timeliness of vaccination is critical to prevent disease outbreaks, protect children through their first 2 years of life, and minimize the need to repeat doses.
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.