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Background: A shortage of Hib vaccine occurred in the United States December 2007-September 2009 resulting in an interim recommendation to defer the booster dose.
Objectives: Quantify effects of the Hib vaccine shortage on vaccination coverage and determine if any demographic subgroups were disproportionately affected by the shortage.
Methods: Data from the 2009 National Immunization Survey (NIS) were divided into 2 groups: 1) children >12 months who thus became eligible to receive their Hib booster dose after the start of the Hib shortage versus, 2) children who were already ≥12 months of age at the start of the shortage. Hib primary series completion and primary series+booster dose completion were estimated, counting vaccinations received up to age 19 months, within these two groups nationally, by state, and within demographic subgroups.
Results: Nationally, there was a large difference in the percentage of children fully vaccinated by 19 months with the primary series+booster dose among children <12 months versus ≥12 months (39.5% versus 66.0%, P<.001). Nationally, there was no difference in Hib primary series completion among children <12 months versus ≥12 months (90.2% versus 91.3%, P=.25). There were no differential effects of the shortage on primary series coverage with regard to children vaccinated at public versus private providers, metropolitan statistical area, or census region. Five states had statistically significant reduced primary series coverage among children <12 months versus ≥12 months. Among children <12 months when the shortage began, the range among states in primary series coverage was 78.1%-96.7%.
Conclusions: In contrast to past shortages, there were no differential effects of the Hib shortage on children visiting private versus public providers. As expected booster dose coverage was much reduced consistent with interim recommendations. Overall, coverage with the Hib primary series remained >78% in all states.