FRIDAY, Aug. 27 (HealthDay News) -- As the result of a recent change to the method for measuring Haemophilus influenzae serotype b (Hib) vaccination coverage, the proportion of children aged 19 to 35 months considered fully vaccinated has dropped by nearly a third, according to an article published in the Aug. 27 issue of the U.S. Centers for Disease Control and Prevention's Morbidity and Mortality Weekly Report.
Tammy A. Santibanez, Ph.D., of the CDC in Atlanta, and colleagues used preliminary National Immunization Survey (NIS) data from the first half of 2009 to assess the change in Hib vaccination coverage estimates resulting from an NIS requirement (which went into effect in January 2009) that vaccination providers report on Hib vaccine product types used, which variously require three or four doses for full vaccination. Before implementation of the requirement, any child who received three doses was classified as fully vaccinated, even if he or she received a vaccine that required four doses.
Using the previous three-dose definition, the researchers found that 82.9 percent of children aged 19 to 35 months were considered fully vaccinated. Under the new requirement, 56.9 percent were considered fully vaccinated, almost a third fewer than previously estimated, while 92.9 percent were classified as having received the primary Hib series recommended by the Advisory Committee on Immunization Practices. The researchers note that the findings were influenced by a shortage of certain Hib vaccine types.
"When interpreting Hib vaccination coverage estimates and analyzing trends with NIS Hib vaccination coverage data in the future, analysts and state immunization programs should be aware of this change in Hib measurement," the authors write.
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