Reviewing the importance of the cold chain in the distribution of vaccines.

Vaccination is an effective public health measure to prevent and control a number of infectious diseases. However, since vaccines are biological products and are sensitive to both heat and cold, they need to be maintained within a narrow range of temperatures, often referred to as the 'cold-chain'. This range, which is between +2°C and +8°C with a target +5°C, does not allow for refreezing or storage at room temperature. This paper discusses the importance of the cold chain, what should be done both to maintain it, and the actions to be taken, should a break be noted. It is important to note the product information supplied with vaccines, which is taken from the summary of product characteristics that forms part of the licensing requirements for each vaccine, and which will state how it should be stored. Using a vaccine that has not been stored according to these instructions constitutes off-label use, for which the individual practitioner must take responsibility. It also emphasises the fragile nature of many public health interventions, maintenance of which require constant vigilance and close cooperation between many groups and individuals.