immunization rate for adults aged 65 and older was 63 percent, up from 58 percent in 1995 (National Center for Health Statistics, 1997).
Despite increased national coverage levels for children and substantial reductions in disparities among racial and ethnic groups, disparities still exist among and within states, as well as within major metropolitan areas. Between 1970 and 1985, surveys of immunization coverage of pre-school-age children revealed racial and ethnic disparities in coverage levels that ranged as high as 26 percentage points (CDC, 1997). The most current available NIS data (July 1998–June 1999) show disparities of 7 to 8.6 percentage points between the immunization coverage levels for non-Hispanic white children and Hispanic and non-Hispanic black children for the 4:3:1:3 series, and lesser disparities for individual vaccine coverage rates among these groups (CDC, 2000e). Much of the difference in coverage levels among racial and ethnic groups is attributable to differences in poverty rates among these groups. Again for the latest annual period, the NIS documented a disparity of 9 percentage points between children living below and those at or above the poverty level for the 4:3:1:3 immunization series (CDC, 2000f). Concentrated poverty, along with the somewhat lower immunization levels for minority children, contributes to the lower coverage levels found in large metropolitan areas.
In 1999, state coverage levels for the 4:3:1:3 series ranged from 71 percent in Arkansas to 89 percent in Vermont, Rhode Island, and Massachusetts (see Figure 2–2). Also in 1999, the coverage levels for the same series were 57 percent in the City of Houston and 73 percent in Dallas County, compared with 76 percent for the rest of Texas. Newark’s coverage level was 67 percent, 18 points lower than the rate for the rest of New Jersey. Chicago’s rate was 70 percent in 1999, compared with 84 percent for the rest of Illinois (CDC, 2000c) (see Table 1–5 in Chapter 1).
Serious disparities in coverage levels also exist within certain large metropolitan areas. Several studies have demonstrated that the NIS, which collects state and county data, is often not sensitive to small area variations, which reveal significant underimmunization among the most disadvantaged populations. For example:
In Marion County, Indiana (Indianapolis), a special survey of poor children found their coverage rate to be 53 percent as compared with an NIS estimate of 78 percent for the county as a whole (Bates and Wolinsky, 1998).
A special survey of children in East Los Angeles found coverage to be 49 percent as compared with NIS data showing a coverage rate of 71 percent for the Los Angeles region (Shaheen et al., 2000).