Vaccine Distribution Logistics

Lyophilized vaccines are typically stored in cold rooms and refrigerators and transported in cold boxes through a 2-8°C cold chain, with a few exceptions, such as those containing Varicella that may be transported at -50°C to -15°C. Vaccines stored as liquid formulations also require a 2-8°C cold chain, while frozen vaccines are stored in freezers at around -20°C or ultralow -80°C freezers. These require cold chains, with cold boxes containing frozen gel packs or preconditioned phase-change materials (PCMs), or insulated boxes with dry ice (e.g., BioNTech's COVID-19 mRNA vaccine). Cryopreserved vaccines require liquid nitrogen (LN2) vapor phase (LNVP) freezers and cold chains that use Dewars with LN₂ or LNVP dry shippers. Storage and distribution methods for all vaccines follow strict national and international guidelines and regulations, maintain an end-to-end chain of custody, and are monitored by temperature data loggers and other devices. Different distribution models are employed for different products and by different countries, ranging from the hub-and-spoke model for LNVP distribution to models with several intermediate stops. Storage and distribution of lyophilized, frozen, and cryopreserved vaccines are described.