Towards Low-Carbon and Climate-Resilient Immunization Supply Chains Through Reduced Waste, Environmental Impact and Carbon Emissions

Background: Immunization programmes deliver substantial public health benefits, but their supply chains depend on energy-intensive cold-chain systems, transport networks, single-use products and waste-treatment pathways that generate greenhouse-gas emissions and environmental health risks. As health systems move towards climate-resilient and low-carbon operations, the environmental footprint of vaccine delivery requires greater policy and programmatic attention. Methods: A narrative review and policy analysis was conducted using peer-reviewed literature, technical reports, programme case studies, institutional guidance, preprints and grey literature published or available between January 2010 and June 2026. Evidence was synthesized across four domains: cold-chain energy use; vaccine transport and logistics; production, packaging and use of vaccines and ancillary supplies; and immunization-related healthcare waste management. The review also examined low-carbon and climate-resilient interventions, including solar refrigeration, logistics optimization, digital stock-management systems, controlled-temperature-chain approaches, safer waste treatment and cold-chain equipment lifecycle management. Findings: The evidence indicates that environmental impacts occur across the vaccine lifecycle but are concentrated in a limited number of supply-chain functions. UNICEF’s international supply-chain emissions baseline estimated 3.9 million tonnes of carbon dioxide equivalent from Scope 3 international supply emissions in 2019, with vaccines, cold-chain equipment, nutrition products and international freight accounting for 80–90% of these emissions. Cold-chain energy use, transport, ancillary supplies and waste treatment emerge as recurring hotspots. Programme evidence from Tunisia, Lebanon, India and Gavi-supported countries demonstrates that solarized cold chains, route optimization, electric vehicles, digital stock visibility and energy-efficient cold-chain equipment can reduce emissions or improve resilience while supporting vaccine availability. However, evidence remains limited on full life-cycle emissions, last-mile transport models, embedded emissions in ancillary supplies, and safe end-of-life management of cold-chain equipment. Interpretation: Low-carbon immunization supply chains are feasible when environmental sustainability is integrated into procurement, energy planning, logistics, digital systems, workforce capacity, waste management and decommissioning. Future assessments should use standardized functional units, such as carbon dioxide equivalent per administered dose and per fully immunized child, to improve comparability and guide investment.