POTENTIAL IMPACT ON VACCINATION COVERAGE LEVELS BY ADMINISTERING VACCINES SIMULTANEOUSLY AND REDUCING DROPOUT RATES

Background: Retrospective immunization coverage surveys conducted duri ng 1991 and 1992 demonstrated that coverage levels for the routine chi ldhood vaccines by 24 months of age in selected urban areas of the Uni ted States ranged from 10% to 52%, far below the US Public Health Serv ice goal of 90%. Therefore, appropriate programmatic changes must be i dentified and incorporated. Methods: We analyzed coverage survey data collected from 21 sites to measure the potential impact on coverage le vels of implementing selected changes in vaccination practices. In a m ultistaged cluster survey design, school health records of kindergarte n or first-grade students were randomly selected and dates of vaccinat ion assessed. We evaluated changes in the vaccination practices, such as eliminating missed opportunities for simultaneous administration of vaccines and ensuring that children initiated the vaccination series on time (ie, by 3 months of age). We then calculated potential increas es in coverage levels for a best-case scenario. Results: From 77% to 9 6% of all children in the 21 sites had received at least one vaccinati on by their first birthday. Children were 2.3 to 17 times more likely to be up to date on their vaccinations by 24 months of age if they wer e up to date at 3 months of age. Each child had many opportunities for the simultaneous administration of diphtheria and tetanus toxoids and pertussis (DTP) vaccine, oral polio vaccine (OPV), and measles-mumps- rub ella (MMR) vaccine that, if used appropriately, could have potenti ally raised coverage levels by 1.2% to 22% (median, 17%). The highest coverage levels could have been attained if all children had started t he series on time and if advantage had been taken of all opportunities for simultaneous vaccination. Coverage levels for four doses of DTP v accine, three doses of OPV, and one dose of MMR vaccine would have inc reased from a baseline of 10% to 52% to levels of 54% to 83%. Conclusi ons: Although the majority of children received a vaccination by their first birthday,the coverage level at 24 months of age was low. Tracki ng systems are needed to ensure that children do not drop out of the s ystem once they have begun the vaccination series. In addition, all ch ildren who are late in beginning their vaccination series are at incre ased risk of not completing the recommended vaccination series on time , and these children need intensive follow-up and recall efforts. Also , providers need to administer all needed vaccines simultaneously.