Modeling the national pediatric vaccine stockpile: Supply shortages, health impacts and cost consequences
Coordinating Office for Terrorism Preparedness and Emergency Response, Centers for Disease Control and Prevention, 1600 Clifton Road, NE, Mailstop K-10, Atlanta, GA 30329-4018, USA. Vaccine
(Impact Factor: 3.62).
08/2010; 28(38):6318-32. DOI: 10.1016/j.vaccine.2010.06.095
Pediatric vaccine stockpiles have been in place in the U.S. since 1983 to address the potential disruption in supply of routine pediatric vaccines. Increases in the number of vaccines recommended for pediatric and adolescent patients have increased the cost of stocking and maintaining the stockpile. Based on a spreadsheet-based model (VacStockpile) we developed, we estimated potential supply shortages of 14 stockpiled vaccines as of August 1, 2008 and its health and financial impacts under various shortage and stockpile scenarios. To illustrate the implications of policy options, we compared "high" to "low" stockpile scenarios. The high stockpile scenario ensures a 6-month vaccine supply to vaccinate all children according to recommended schedules. The low scenario comprised of 50% of the high scenario or existing stocks, whichever is smaller. For each vaccine, we used a weighted average of five shortage scenarios ranging from 0% to 100%, in 25% increments. Demand for each vaccine was based on current distribution or birth cohort size. The probabilities of shortages were based on number of manufacturers, market stability, history of manufacturing problems, and production complexity. CDC contract prices were used to estimate costs. Expert opinion and literature provided estimates of health impacts due to shortages. Applying the probabilities of shortages to all vaccines in a single year, the "low" scenario could cost $600 million, with 376,000 vaccine-preventable cases occurring and 1774 deaths. The "high" scenario could cost $2 billion, with an additional $1.6 billion initial stocking, and result in 7100 vaccine-preventable cases occurring and 508 deaths. Based on the assumptions in the model, there is the potential for large differences in outcomes between the scenarios although some outcomes could potentially be averted with measures such as catch-up campaigns after shortages. Using the VacStockpile policy makers can readily evaluate the implications of assumptions and decide which set of assumptions they wish to use in planning.
Available from: Sheldon H Jacobson
- "Our model considers unexpected supply interruptions of stochastic duration, and also the capacity of the system to restore the vaccine supply . Shrestha et al.  erroneously describe the conclusions of our studies, in which we conclude that the current recommendation of holding enough vaccines to satisfy a 6-month demand is only valid for attenuating shortages lasting up to 6-months, and that given that the typical vaccine supply interruptions have lasted longer than that, the current stockpile recommendations are inadequate. "
Available from: Kathleen M. Gallagher
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ABSTRACT: The United States eliminated indigenous wild polioviruses (WPVs) in 1979 and switched to inactivated poliovirus vaccine in 2000, which quickly ended all indigenous live poliovirus transmission. Continued WPV circulation and use of oral poliovirus vaccine globally allow for the possibility of reintroduction of these viruses. We evaluated the risk of a U.S. polio outbreak and explored potential vaccine needs for outbreak response.
We synthesized information available on vaccine coverage, exemptor populations, and population immunity. We used an infection transmission model to explore the potential dynamics of a U.S. polio outbreak and potential vaccine needs for outbreak response, and assessed the impacts of heterogeneity in population immunity for two different subpopulations with potentially low coverage.
Although the risk of poliovirus introduction remains real, widespread transmission of polioviruses appears unlikely in the U.S., given high routine coverage. However, clusters of un- or underimmunized children might create pockets of susceptibility that could potentially lead to one or more paralytic polio cases. We found that the shift toward combination vaccine utilization, with limited age indications for use, and other current trends (e.g., decreasing proportion of the population with immunity induced by live polioviruses and aging of vaccine exemptor populations) might increase the vulnerability to poliovirus reintroduction at the same time that the ability to respond may decrease.
The U.S. poliovirus vaccine stockpile remains an important resource that may potentially be needed in the future to respond to an outbreak if a live poliovirus gets imported into a subpopulation with low vaccination coverage.
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