bilities that require coordination and integration through investments in infrastructure.
Finding 2–3. The increasing complexity of the immunization schedule necessitates intensive surveillance and records management for young children, especially for vulnerable populations who may not have a regular source of health care and are therefore at greatest risk of low immunization coverage. This complexity is likely to increase during periods of reform and realignment within the health care delivery system; thus, greater oversight and monitoring are required to ensure that disparities in immunization coverage rates do not grow.
Despite the increasing change and complexity affecting the national immunization effort, the incidence of VPDs has decreased, and important objectives for national coverage were partially met in the 1990s. Yet as noted earlier, persistent problems, such as disparities in childhood coverage levels, low adult immunization rates, ethnic disparities in adult immunization rates, and concerns about the quality of surveillance tools, continue to plague the system.
The successes of the national immunization effort are most evident in the dramatic decrease in VPD incidence in the 1990s (CDC, 1999a). Only one case of diphtheria was reported in both 1998 and 1999 (CDC, 1999f; information provided by CDC). Polio has been eradicated in the Western Hemisphere, and global polio eradication is expected in this decade (information provided by CDC).
Certain childhood and adult coverage goals have been achieved as well. By 1996, more than 90 percent of American children aged 19 to 35 months had received the first and most critical doses in the primary series for DTP, Haemophilus influenzae type b (Hib), polio, and measles vaccines (NVAC, 1999a). The complete immunization of 79.2 percent of 2-year-old children for the 4:3:1:3 series (four or more doses of DTP, three or more doses of poliovirus, one or more dose of any measles-containing vaccine, and three or more doses of Hib) in 1998 is another major accomplishment, made possible by a remarkable federal-state partnership effort (CDC, 1998a), although approximately 1 million 2-year-olds still need one or more vaccine doses to be fully immunized (NVAC, 1999a). Strides have also been made in adult immunizations. In 1997, the national influenza