Undervaccinated African-American preschoolers: a case of missed opportunities

To identify factors associated with undervaccination of African-American preschoolers, to describe the number of vaccination visits made by undervaccinated children and the number of visits needed to be series complete, and to describe the children who did not receive the single dose of measles-containing vaccine recommended for preschoolers.

We used the 1999 National Immunization Survey (NIS) to describe vaccination coverage for the 4:3:1:3 vaccine series (four doses of diphtheria and tetanus toxoids and pertussis vaccine, three doses of poliovirus vaccine, one dose of any measles-containing vaccine, and three doses of Haemophilus influenzae type b vaccine) among non-Hispanic, African-American preschoolers due to concerns that they may be at risk of undervaccination. Children who did not complete this basic vaccine series were classified for further analysis according to the number of doses they lacked (i.e., one dose missed, two or three doses missed, or four or more doses missed). Significant associations between demographic characteristics and vaccination status or degree of undervaccination were determined.

Of the 26.2% of African-American preschoolers who did not complete the 4:3:1:3 vaccine series, 40.3% lacked one, 35.3% lacked two or three, and 25.0% lacked four or more doses of vaccine. Children who did not complete the 4:3:1:3 vaccine series were less likely to have married mothers, were less likely to have mothers aged > or = 35 years, or were less likely to be up to date at age 3 months than the children who completed the 4:3:1:3 vaccine series. Among the undervaccinated, 63.7% had a sufficient number of vaccination visits to have completed the basic series. However, most (78.7%) of the severely undervaccinated (children who lacked more than three doses of vaccine) had three or fewer vaccination visits. For 72.6% of the undervaccinated preschoolers, only one additional vaccination visit was needed to complete the 4:3:1:3 vaccine series; among these, 78.3% had an adequate number of vaccination visits to have completed the series. Overall, 9.9% of the African-American children aged 19 to 35 months (i.e., approximately 85,000 African-American children aged 19 to 35 months) were at risk for measles. Among the children who lacked more than three doses of vaccine, 68.1% were at risk.

Our study suggests that the estimated coverage of 73.8% for the 4:3:1:3 vaccine series among African-American children aged 19 to 35 months was not a result of limited access to care. On the contrary, 90.5% of African-American children had enough vaccination visits to complete the series. To raise coverage and prevent potential outbreaks, providers should assess each child's vaccination status at every visit, and administer all needed vaccinations at that time. For the most severely undervaccinated children, this strategy may not be adequate, because they did not have the minimum number of vaccination visits required for series completion. For these children, other strategies are needed for increasing vaccination coverage.