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Cold chain refers to a temperature-controlled supply chain. An unbroken cold chain is an uninterrupted series of storage and distribution activities which maintain a given temperature range. Cold chains are common in the food and pharmaceutical industries and also some chemical shipments. One common temperature range for a cold chain in pharaceutical industries is 2 to 8 °C. but the specific temperature (and time at temperature) tolerances depend on the actual product being shipped.

This is important in the supply of vaccines to distant clinics in hot climates served by poorly developed transport networks. Disruption of a cold chain due to war may produce consequences similar to the Smallpox outbreaks in the Philippines during the Spanish-American war.

Traditionally all historical stability data developed for vaccines was based on the temperature range of 2-8 C. With recent development of biological products by former vaccine developers, biologics has fallen into the same category of storage at 2-8 C due to the nature of the products and the lack of testing these products at wider storage conditions.

Traditionally the industry believed that the cold chain process could not be validated. With the proper understanding of the entire process, this process is validateable. Please see PDA Technical Report # 39 for a rough summary of how this process can be validated.

The overall approach to Validation of a distribution process is done by building more and more qualification on top of each other to get to a validated state. This is done by executing a Design Qualification on the packaging components. Next an Operational Qualification that demonstrates the process performs at the operational extremes. The final piece is the Performance Qualification that demonstrates that what happens in the real world is within the limits of what was demonstrated in the Operational Qualification limits.

The PDA's Technical Report states that a Component Qualfication is required, but in reality that is a Design Qualification. This was purposelly put into the document in order to protect the intellectual property of one of the authors of the document.

Performing thermal testing can also help with validating the cold chain. Certified test labs use environmental chambers to simulate ambient profiles that a package may encounter in the distribution cycle. Thermocouple probes measure temperatures within the product load to assure that temperatures do not reach outside of the required temperature range. Testing can be completed in triplicate based on a qualification protocol to create a final qualification report that can be used to defend the configuration when audited by the FDA.

Additionally, it is critical to develop Cold Chain Management Information Systems (MIS) for monitoring equipment status and vaccine storage capacity, particularly in developing countries in which vaccines are in great part administered by rural clinics. Unless vaccine shipment, inventory, consumables, equipment and spares are tracked, there is no guarantee that the vaccine will be effective.

• Bacterial growth
• HACCP
• Logistics
• Packaging
• Shelf life
• Specification
• Temperature control
• Thermal decomposition
• Thermal insulation
• Tolerance (engineering)
• Transportation management system

• "Manual on the Management, Maintenance and Use of Blood Cold Chain Equipment", World Health Organization, 2005, ISBN: 9241546735
• "Cold Chain Management", 2003, 2006, [1]
• Clive, D., "Cold and Chilled Storage Technology", 1997, ISBN: 0751403911
• Austraila Cold Chain Center, [2]
• EN 12830:1999 Temperature recorders for the transport, storage and distribution of chilled, frozen and deep-frozen/quick-frozen food and ice cream