Cold Chain

A supply chain that uses refrigeration to keep temperature sensitive goods such as pharmaceuticals, produce, seafood and frozen food viable from production to destination. Its defining requirement is that the refrigerated sequence remain unbroken through production, storage and distribution; it began with the ice trade, reefer ships and refrigerator cars of the mid nineteenth century. Cold chains are tiered by temperature: an ordinary refrigerated chain runs between about 2 and 8 degrees Celsius and covers most vaccines and produce, a frozen chain holds about minus 20 degrees Celsius for products such as varicella and zoster vaccines, and an ultralow or deep freeze chain reaches about minus 70 degrees Celsius for products such as the Pfizer-BioNTech COVID-19 vaccine, an infrastructure tier only a minority of countries can sustain.