Shaofu Chen

Influenza vaccine coverage and missed opportunities among inner-city children aged 6 to 23 months: 2000-2005.

OBJECTIVE. In 2002, the Advisory Committee on Immunization Practices recommended universal influenza vaccination of 6- to 23-month-olds. Little is known about coverage and missed opportunities for influenza vaccination at inner-city practices. The objective of this study was to assess the 2000–2001 to 2004–2005 coverage and the prevalence of missed opportunities for influenza vaccination among inner-city children. METHODS. We conducted a retrospective review for the 2000–2001 to 2004–2005 influenza seasons at a practice network in New York City. The study population included 5 annual cohorts of 6- to 29-month olds as of March 31 of each year with ≥1 visit to the network in the previous 12 months (n = 7063). Immunization data were obtained from the network registry and the New York Citywide Immunization Registry. Coverage levels were estimated for 1 dose (partial) and 2 doses (full). Missed opportunities were assessed for visits within each influenza season. RESULTS. Coverage rose steadily throughout the 5 years (full: 1.6% to 23.7%; partial: 1.5% to 18.1%). The relationship between year and coverage was linear. Missed opportunities occurred in 82% of visits and were more common for first (89%) than for repeat doses (38%). Missed opportunities per child per season decreased from 2.9 to 2.0 during the study period. CONCLUSIONS. Influenza vaccine coverage among 6- to 23-month-olds at inner-city practices increased steadily from 2000–2001 through 2004–2005, and the prevalence of missed opportunities per child decreased. However, coverage remained suboptimal, with most of children not vaccinated or undervaccinated. Missed opportunities were major contributors to low coverage.

Early Continuity of Care and Immunization Coverage

OBJECTIVE We examined the relationship between early and exclusive continuity of care at the initial source of care and immunization coverage. METHODS We used a cohort study design with 641 randomly selected children initiating care before 3 months and making 2 or more visits to an inner-city practice network. We used 2 complementary data sources: medical records and the New York City Department of Health Citywide Immunization Registry. Immunization measures were cumulative age appropriate and up-to-date at 18 months (UTD18). RESULTS There was a gradual attrition from the initial source of care. By 18 months, less than half the children (46%) remained in care. Regardless of continuity, nearly half (42%) had used other immunization providers. The initial source of care contributed most immunizations (89%-94%); however, across all levels of continuity, children who also used other providers had higher immunization rates. We found a threshold effect of continuity beginning at 12 months: children in care from 12 to 14 months were 17.5 times more likely to be UTD18 than those in care less than 6 months. Each additional period in care increased the time remaining current with immunizations. Among children UTD18, 88% were in care at 11 months compared with 38% among those not UTD18, a 50% difference. CONCLUSIONS Continuity of care at the initial source of care had a significant and lasting impact on immunization coverage, even if not used exclusively. Interventions promoting continued use of the medical home over the first 2 years of life may help improve immunization coverage.

Community-Provider Partnerships to Reduce Immunization Disparities: Field Report From Northern Manhattan

In 1996 we launched a community-provider partnership to raise immunization coverage for children aged younger than 3 years in Northern Manhattan, New York City. The partnership was aimed at fostering provider knowledge and accountability, practice improvements, and community outreach. By 1999 the partnership included 26 practices and 20 community groups. Between 1996 and 1999, immunization coverage rates increased in Northern Manhattan 5 times faster than in New York City and 8 times faster than in the United States (respectively, 3.4% vs 0.4% [t = 6.05, p < 0.001] and vs 0.6% [t = 5.65, p < 0.001]). The coverage rate for Northern Manhattan stayed constant through 2000, although it declined during this period for the United States and New York City. We attribute the success at reducing the gap to the effectiveness of our partnership.

Effectiveness of a Community Coalition for Improving Child Vaccination Rates in New York City

We used a retrospective, matching, birth cohort design to evaluate a comprehensive, coalition-led childhood immunization program of outreach, education, and reminders in a Latino, urban community. After we controlled for Latino ethnicity and Medicaid, we found that children enrolled in the program were 53% more likely to be up-to-date (adjusted odds ratio = 1.53; 95% confidence interval = 1.33, 1.75) and to receive timely immunizations than were children in the control group (t = 3.91). The coalition-led, community-based immunization program was effective in improving on-time childhood immunization coverage.

Is Underimmunization Associated With Child Maltreatment

OBJECTIVE To assess the relationship between underimmunization and child maltreatment among children referred to a child advocacy center for a child maltreatment evaluation. METHODS We conducted a secondary data analysis of 399 children aged 3 to 48 months who were referred to a child advocacy center at an academic medical center. The primary independent variable was age-appropriate immunization status. The dependent variable was maltreatment (confirmed, suspected, or ruled out). Multivariate models were used to control for insurance, race/ethnicity, and maternal education. RESULTS At 3 and 7 months of age, underimmunized children were significantly more likely to have confirmed maltreatment than children whose immunizations were up to date (at 3 months, 32.0% vs 17.6%, P < .05; at 7 months, 23.7% vs 8.6%, P < .01). At 19 months, rates were not significantly different (16.1% vs 24.1%, P = .33). In multivariate analyses, children underimmunized at 3 or 7 months of age were 4 times more likely to have confirmed maltreatment compared with children whose immunizations were up to date (at 3 months, adjusted odds ratio [AOR], 3.97, 95% confidence interval [95% CI], 1.67-9.49; at 7 months, AOR, 4.79, 95% CI, 1.47-15.66). This relationship was statistically significant for children evaluated for physical abuse (AOR, 4.34, 95% CI, 1.18-16.02), but not for sexual abuse. CONCLUSIONS Underimmunization at 3 and 7 months of age was associated with confirmed maltreatment, specifically physical abuse, in children evaluated for child maltreatment. The association between underimmunization and child abuse in the general population deserves further study.

The impact of DTaP-IPV-HB vaccine on use of health services for young infants.

Background: In 2003, a pentavalent vaccine (diphtheria, tetanus and acellular pertussis, injectable polio and hepatitis B) was introduced into the childhood vaccination schedule. A premarketing study showed a higher incidence of fever than with the vaccines administered separately. Because fevers in young infants prompt medical evaluations, this study examines the impact of this vaccine (DTaP-IPV-HB) on subsequent use of health services. Methods: We compared use of health services among 6- to 10-week-old infants receiving DTaP-IPV-HB (n = 1776) with a historical control receiving the prior schedule (n = 2162) at an inner-city practice network. Data sources included a hospital immunization registry and medical records. Outcome measures were visits to the emergency department and ambulatory practices, fever, tests, antibiotics and hospitalizations. Outcomes were stratified by age (<8, 8–10 weeks) and days since vaccination (3, 7). Results: Infants vaccinated with DTaP-IPV-HB were more likely to visit the ED (1.2% versus 0.6%, P = 0.03) and receive tests (47.6% versus 8.3%, P = 0.03) within 3 days of vaccination compared with the controls. Multivariate analysis showed infants vaccinated with DTaP-IPV-HB had a 7-fold increased risk of receiving a full sepsis workup and a 3-fold increased risk of receiving antibiotics within 7 days of vaccination. Medical evaluations decreased over time after implementation of the DTaP-IPV-HB vaccine. Concurrently, the rate of vaccination for infants <8 weeks markedly dropped. Conclusions: The DTaP-IPV-HB vaccine was associated with increased use of health services in the emergency department, but these associations lessened over time. These findings reveal a conflict between the obligation of timely and efficient vaccination with the medical management of febrile young infants.

Impact of the Advisory Committee on Immunization Practices’ 4-Day Grace Period in a Low-Income Community

BACKGROUND In 2002, the Advisory Committee on Immunization Practices (ACIP) recommended vaccine doses administered < or = 4 days before the minimum age or interval be counted as valid. The study objective was to assess the impact of the 4-day grace period on the need for revaccination and associated costs in a low-income community, compared to standard practice (i.e., repeating all doses that fall outside current ACIP guidelines). METHODS From 1999 to 2001, semi-annual immunization assessments of 8293 randomly selected children, aged 19-35 months, were conducted at a 16-practice network serving an underserved community in New York City. Outcome measures were rates of antigen-specific invalid doses and number of children needing revaccination, with and without the 4-day grace period. Revaccination costs were based on the Vaccines for Children (VFC) price list. RESULTS The 4-day grace period reduced the number of children needing revaccination from 17.1% to 12.0%, a drop of 30%. The rates of invalid doses decreased from 1.9% to 1.3%, a drop of 33%. Invalid doses for hepatitis B (HepB)-2 decreased by two thirds (69.7%); for diphtheria-tetanus-acellular pertussis (DTaP)-1, Haemophilus influenzae type b (Hib)-1 and Hib-3 by half (44.9%-50.0%); for Polio-1, Polio-2, Polio-3, and measles-mumps-rubella (MMR) by one third (31.6%-33.3%); and for DTaP-2, DTaP-3, HepB-3, and varicella by nearly one quarter (20.0%-24.0%). At these rates, revaccinating 100,000 children younger than age 3 years would cost 213,588 dollars per year, compared to 152,539 dollars with the 4-day grace period, in vaccine costs alone. CONCLUSIONS In a low-income community, ACIPs 4-day grace period made a significant impact on the number of children requiring revaccination and on revaccination costs. However, the number of children needing revaccination remains high.