Cold chain

Why it matters

Excess heat or excess cold reduces vaccine potency [1]. WHO states that safe, effective and reliable cold chain equipment is crucial to protecting the public health value of vaccines, and of the investment made to develop, procure and deliver them [2]. For an immunisation programme, a break in the cold chain can mean a dose that is given but does not protect.

Key points

• The Open University immunisation module describes three components: equipment for transport and storage, well trained personnel, and efficient management procedures [1].
• Monitoring tools include vaccine vial monitors, freeze indicators, thermometers and the shake test [1].
• WHO prequalifies cold chain equipment through its Performance, Quality and Safety programme, which covers refrigerators and freezers, including solar direct drive refrigerators, equipment monitoring systems and temperature monitoring devices [2].
• Stock data and cold chain data belong together. In three regions of Tanzania, an integrated electronic immunisation registry and logistics system was associated with the monthly average vaccine stockout rate falling from 7.1% to 2.1% in the analysed sample [3].

Sources

1. Immunization Module: The Cold Chain, The Open University, OpenLearn Create, accessed 2026
2. WHO Immunization Devices Prequalification: 2025 to 2030 Strategy, World Health Organization, 2025
3. The impact of an integrated electronic immunization registry and logistics management information system on vaccine availability in three regions in Tanzania, Vaccine, 2020