Last week was World Immunisation Week, celebrating and raising awareness for one of the greatest medical interventions known to mankind: the vaccine. But vaccination has a lot of problems, one being the cold chain.
The cold chain refers to the physical supply of refrigerated vaccines from the manufacturer to the person being immunised. This constant controlled temperature is required to limit any damage done to the vaccine components, which themselves are biological samples.
For example, the live-attenuated measles vaccine used across the world will rapidly lose it's ability to protect you if it is stored at 37 degree celsius; it can be stored for much longer at 4 degrees. This makes the cold chain essentially one of the most important components of global health strategies. For another take on the cold chain and developments to make it better, read Vincent Racaniello's post over at Virology Blog last year.