These strategies are complementary to vaccine purchase and service-delivery efforts intended to increase coverage levels within populations that require additional assistance in achieving up-to-date immunizations. Each strategy consists of several different types of interventions. TFCPS recently reviewed the available literature to determine areas of best practice (Briss et al., 2000). An abbreviated summary of the TFCPS findings is presented here to demonstrate the impact of public health infrastructure investments on immunization coverage rates.
The out-of-pocket costs of immunization constitute a barrier to obtaining vaccinations for many clients (Cutts et al., 1992). Providers are more likely to refer children with less public or private insurance coverage to other sites for vaccination, and referral practices are known to have adverse effects on both the timing and rate of immunization (Bennett et al., 1994; Mainous and Hueston, 1995; Ruch-Ross and O’Connor, 1994; Taylor et al., 1997; Zimmerman et al., 1997).
Reducing out-of-pocket costs improves vaccination coverage for diverse age groups and populations in a range of settings, from individual clinics, to statewide programs, to national efforts such as the Vaccines for Children (VFC) program (Briss et al., 2000). These positive effects have been reported whether the reduced-cost intervention has been used alone or as part of a multicomponent intervention (such as client or provider reminder-recall, communitywide education, expansion of access in health care settings, and provider education). The overall median coverage difference was found to be 10 percent (range of 8 to 35 percent). On the basis of this evidence, TFCPS strongly recommended reducing out-of-pocket costs as an effective strategy to improve vaccination coverage (Briss et al., 2000).
Although poverty is commonly accepted as a significant cause of discrepancies among immunization coverage rates, low rates of immunization coverage have been reported among populations for which cost is not a barrier (Orenstein et al., 1999). In one survey of 2-year-old children of employees of a large corporation, for example, only 65 percent of the children who had medical insurance coverage for immunizations had received the 4:3:1 series (four DTP, three polio, and one MMR) (Fielding et al., 1994).13 There were also no differences in coverage found in a study that compared private practices in states with and without universal purchase policies (Taylor et al., 1997). The families surveyed in this study, however, were well educated, of moderate to high socioeconomic status, and therefore least likely to benefit from free vaccines (Orenstein et al., 1999).