Global, regional, and national impact of the Expanded Programme on Immunization against 14 pathogens from 1974 to 2024: an economic evaluation

BACKGROUND: 2024 marked the 50th anniversary of the Expanded Programme on Immunization (EPI), launched by WHO. Despite its crucial role in preventing infectious diseases, EPI's 50-year economic impact has not been systematically evaluated. This study aims to estimate the benefit-cost ratios (BCRs) and incremental cost-effectiveness ratios (ICERs) of EPI at global, regional, and national levels. METHODS: We conducted an economic evaluation of EPI for 14 globally important pathogens with robust long-term data availability: Corynebacterium diphtheriae (diphtheria), Haemophilus influenzae type b, hepatitis B virus (hepatitis B), Japanese encephalitis virus (Japanese encephalitis), measles virus (measles), Neisseria meningitidis group A (meningitis A), Streptococcus pneumoniae, Bordetella pertussis (pertussis), poliovirus (polio), rotavirus, rubella virus (rubella), Clostridium tetani (tetanus), Mycobacterium tuberculosis (tuberculosis), and yellow fever virus (yellow fever) from Jan 1, 1974, to Dec 31, 2024, across 194 WHO member states. We compared costs (procurement, administration, and family additional costs from time spent synthesised from authoritative global databases and systematic literature reviews) and benefits (primarily averted mortality retrieved from published global burden estimates) between observed EPI implementation and a counterfactual scenario of no vaccination, from which BCRs and ICERs were derived. FINDINGS: From 1974 to 2024, the cost of EPI reached US937 billion (95% CI 699-1187), offset by 15 050 billion (12 609-17 605) in averted productivity losses due to mortality (aggregate BCR 16·06 95% CI 10·62-25·20; ICER cost-saving). Immunisation against all 14 pathogens showed favourable economic outcomes. Measles vaccination produced the highest BCR (73·97 45·78-124·06), and the ICERs for all vaccines remained below conventional cost-effectiveness thresholds. EPI against 14 pathogens in aggregate achieved cost savings (BCR>1) in all 194 WHO member states. Economic returns varied across six WHO regions and four World Bank income groups, with the Eastern Mediterranean region (BCR 17·22 11·22-28·67) and low-income countries (BCR 23·63 16·87-34·32) showing the highest BCRs. INTERPRETATION: The 50-year EPI has proven highly cost-effective at global, regional, and national levels, and remains a worthwhile investment. The EPI delivered impactful life-saving benefits and favourable economic returns, especially in high-burden and low-income settings. FUNDING: The National Natural Science Foundation of China, the China Postdoctoral Science Foundation, the Vaccine Impact Modelling Consortium, and the Japan Agency for Medical Research and Development.