For Transportation of Vaccines, this recommendation from WHO 5 also applies when using cold boxes and vaccine carriers. Because vaccines are almost invariably distributed as a mixed consignment, with both freeze-sensitive and freeze-tolerant vaccines packed together in the same cold box or carrier, it is extremely important that routine supplies to each level should not become frozen during transport. If this occurs, all the freeze-sensitive vaccines, including the DPT, the DPT-HepB, the TT and the HepB birth dose vials, will be destroyed before reaching their destination. Therefore, WHO recommends that ice packs used during transportation should not be frozen when they are placed inside the cold box or vaccine carrier. The use of frozen ice packs will risk freezing vaccines during transport, especially during the winter months, and therefore only non-
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frozen or conditioned ice packs should be used for vaccine transport. This recommendation is especially relevant in DPR Korea, where the winter months are long and often very severe, and air temperatures may be well below freezing point for extended periods.