title: Augmenting transport versus increasing cold storage to improve vaccine supply chains.
abstract: BACKGROUND
  When addressing the urgent task of improving vaccine supply chains, especially to accommodate the introduction of new vaccines, there is often a heavy emphasis on stationary storage. Currently, donations to vaccine supply chains occur largely in the form of storage equipment.
  
  
  METHODS
  This study utilized a HERMES-generated detailed, dynamic, discrete event simulation model of the Niger vaccine supply chain to compare the impacts on vaccine availability of adding stationary cold storage versus transport capacity at different levels and to determine whether adding stationary storage capacity alone would be enough to relieve potential bottlenecks when pneumococcal and rotavirus vaccines are introduced by 2015.
  
  
  RESULTS
  Relieving regional level storage bottlenecks increased vaccine availability (by 4%) more than relieving storage bottlenecks at the district (1% increase), central (no change), and clinic (no change) levels alone. Increasing transport frequency (or capacity) yielded far greater gains (e.g., 15% increase in vaccine availability when doubling transport frequency to the district level and 18% when tripling). In fact, relieving all stationary storage constraints could only increase vaccine availability by 11%, whereas doubling the transport frequency throughout the system led to a 26% increase and tripling the frequency led to a 30% increase. Increasing transport frequency also reduced the amount of stationary storage space needed in the supply chain. The supply chain required an additional 61,269L of storage to relieve constraints with the current transport frequency, 55,255L with transport frequency doubled, and 51,791L with transport frequency tripled.
  
  
  CONCLUSIONS
  When evaluating vaccine supply chains, it is important to understand the interplay between stationary storage and transport. The HERMES-generated dynamic simulation model showed how augmenting transport can result in greater gains than only augmenting stationary storage and can reduce stationary storage needs.
authors.affiliation: Public Health Computational and Operational Research-PHICOR Group, School of Medicine and Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America.
authors.forename: Leila A
authors.initials: LA
authors.lastname: Haidari
authors.forename: Diana L
authors.initials: DL
authors.lastname: Connor
authors.forename: Angela R
authors.initials: AR
authors.lastname: Wateska
authors.forename: Shawn T
authors.initials: ST
authors.lastname: Brown
authors.forename: Leslie E
authors.initials: LE
authors.lastname: Mueller
authors.forename: Bryan A
authors.initials: BA
authors.lastname: Norman
authors.forename: Michelle M
authors.initials: MM
authors.lastname: Schmitz
authors.forename: Proma
authors.initials: P
authors.lastname: Paul
authors.forename: Jayant
authors.initials: J
authors.lastname: Rajgopal
authors.forename: Joel S
authors.initials: JS
authors.lastname: Welling
authors.forename: Jim
authors.initials: J
authors.lastname: Leonard
authors.forename: Sheng-I
authors.initials: SI
authors.lastname: Chen
authors.forename: Bruce Y
authors.initials: BY
authors.lastname: Lee
mesh_terms: D015925:Cryopreservation; D009548:Niger; D014186:Transportation; D014612:Vaccines / Q000600:supply & distribution*
chemical_list: D014612:Vaccines