摘要：Objectives. We investigated whether introducing the rotavirus and pneumococcal vaccines, which are greatly needed in West Africa, would overwhelm existing supply chains (i.e., the series of steps required to get a vaccine from the manufacturers to the target population) in Niger. Methods. As part of the Bill and Melinda Gates Foundation–funded Vaccine Modeling Initiative, we developed a computational model to determine the impact of introducing these new vaccines to Niger's Expanded Program on Immunization vaccine supply chain. Results. Introducing either the rotavirus vaccine or the 7-valent pneumococcal conjugate vaccine could overwhelm available storage and transport refrigerator space, creating bottlenecks that would prevent the flow of vaccines down to the clinics. As a result, the availability of all World Health Organization Expanded Program on Immunization vaccines to patients might decrease from an average of 69% to 28.2% (range = 10%–51%). Addition of refrigerator and transport capacity could alleviate this bottleneck. Conclusions. Our results suggest that the effects on the vaccine supply chain should be considered when introducing a new vaccine and that computational models can help assess evolving needs and prevent problems with vaccine delivery. Both rotavirus and pneumococcal disease cause high morbidity and mortality in West African countries. In 2004, more than 65% of deaths associated with rotavirus infection occurred in 11 Asian and African countries. Of these countries, Niger had the highest under-5 mortality (392 deaths/100 000 population younger than 5 years). 1 Each year, Africa alone has 1 to 4 million pneumococcal pneumonia cases, contributing a substantial proportion of the 814 000 annual pneumococcal deaths among children younger than 5 years worldwide. 2 Although the rotavirus vaccine (RV) and the 7-valent pneumococcal conjugate vaccine (PCV-7) could meet significant needs in West Africa, it is unclear whether the supply chains (i.e., the series of steps required to get a vaccine from the manufacturers to the target population of countries such as Niger) can handle the introduction of these vaccines. 3 When Merck's RotaTeq (798 cm3/10-dose box) and GlaxoSmithKline's Rotarix (259.8 cm3/1-dose box) were introduced in Latin America in 2006 to 2007, these bulky vaccines displaced existing Expanded Programs on Immunization (EPI) vaccines in already limited refrigerator space and forced overburdened health care workers to carry additional thermoses to transport the new vaccines. 4 To help determine the potential effects on the supply chain of introducing RV or PCV-7 to Niger, the Vaccine Modeling Initiative, funded by the Bill and Melinda Gates Foundation, developed a computational model of the entire Niger vaccine supply chain. We conducted several experiments with different vaccine presentations to explore their effects on storage and transport. We did not consider such resources as buildings, personnel, or vaccine safety injection equipment. We also sought to identify modifications that vaccine policymakers, logisticians, and manufacturers may have to make to facilitate new vaccine introduction.
