An analysis of the pediatric vaccine supply shortage problem

In 2002, several factors resulted in pediatric vaccine manufacturers not being able to produce a sufficient number of vaccines to vaccinate all the children in the United States according to the Recommended Childhood Immunization Schedule. The resulting vaccine supply shortage resulted in thousands of children not being fully immunized according to this schedule, and hence, created an unnecessary risk for epidemic outbreaks of several childhood diseases. The Centers for Disease Control and Prevention responded to this crisis by using pediatric vaccine stockpiles to mitigate the impact of future shortages. This paper presents a stochastic model that captures the vaccine supply during production interruptions. This model is used to assess the impact of pediatric vaccine stockpile levels on vaccination coverage rates, by considering the probability that all children can be immunized according to the Recommended Childhood Immunization Schedule over a given time period and the expected minimum vaccine supply. The model is also used to assess the proposed pediatric vaccine stockpile levels recommended by the United States Department of Health and Human Services. The results of this analysis suggest that the proposed vaccine stockpile levels are adequate to meet future vaccine production interruptions, provided that such production interruptions do not last more than six months (which is not surprising, given that is the time period for which they were designed). However, given that recent vaccine production interruptions have lasted (on average) for over one year, the proposed vaccine stockpile levels are insufficient to meet the nation's pediatric immunization needs during such time periods, which in turn could lead to localized and/or widespread disease outbreaks. Moreover, a moderate investment in higher vaccine stockpile levels would lead to a significantly reduced risk of such events.