“Cold chain” refers to the process used to maintain optimal conditions during the transport, storage, and handling of vaccines, starting at the manufacturer and ending with the administration of the vaccine to the client. The optimum temperature for refrigerated vaccines is between +2°C and +8°C. For frozen vaccines the optimum temperature is -15°C or lower. In addition, protection from light is a necessary condition for some vaccines.
Proper storage temperatures must be maintained at every link in the chain.
Importance of Maintaining the Cold Chain Vaccines are sensitive biological products which may become less effective, or even destroyed, when exposed to temperatures outside the recommended range. Cold-sensitive vaccines experience an immediate loss of potency following freezing. Vaccines exposed to temperatures above the recommended temperature range experience some loss of potency with each episode of exposure. Repetitive exposure to heat episodes results in a cumulative loss of potency that is not reversible. However, information on vaccine degradation is sparse and multipoint stability studies on vaccines are difficult to perform. In addition, information from manufacturers is not always available, so it can be difficult to assess the potency of a mishandled vaccine(1). Maintaining the potency of vaccines is important for several reasons. § There is a need to ensure that an effective product is being used. Vaccine failures caused by administration of compromised vaccine may result in the re-emergence or occurrence of vaccine preventable disease. § Careful management of resources is important. Vaccines are expensive and can be in short supply. Loss of vaccines may result in the cancellation of immunization clinics resulting in lost opportunities to immunize. § Revaccination of people who have received an ineffective vaccine is professionally uncomfortable and may cause a loss of public confidence in vaccines and/or the health care system.
Temperatures falling outside the recommended range require immediate action to avoid loss of product.
When a cold chain break is identified after a vaccine has been administered, consult your local public health office or immunization program* for advice. The type of vaccine, duration and temperature of the exposure will be taken into account when assessing the situation. Serological testing or revaccination may be suggested(4).
Vaccines are sensitive biological products that may become less effective, or even destroyed, when exposed to temperatures outside the recommended range and/or on exposure to direct sunlight or fluorescent light.
he Effective Cold Chain Three main elements combine to ensure proper vaccine transport, storage, and handling. - Trained personnel - Transport and storage equipment - Efficient management procedures