Vaccine transport and storage: environmental challenges.

This paper describes the current status of the vaccine cold chain that was developed in the 1970s. It then describes the changes that are likely to take place in the next 5 to 10 years and their potential impact on the existing system. For more than 20 years, the cold chain system and vaccine handling rules have been set to the speed of the most fragile of the EPI vaccines namely: Oral Polio Vaccine. This has led to the establishment by WHO of stringent vaccine handling rules and Standard Performance Specifications for cold chain equipment. Major changes are occurring that will impact on immunization programmes: The introduction of Vaccine Vial Monitor (VVM), the prospect of an increase in the stability of OPV and the worldwide ban on refrigeration gases and insulation foaming agents.