Public Health · 1974
WHO Expanded Programme on Immunization (EPI) launched
When the 27th World Health Assembly convened in 1974, fewer than 5% of children in low- and middle-income countries had received any of the six vaccines against diphtheria, tetanus, pertussis, polio, measles, or tuberculosis. Childhood death from these diseases was routine, not exceptional. The Assembly's response was to create the Expanded Programme on Immunization, an initiative that would attempt to reach every child on earth with a standardized package of antigens.
WHO Director-General Halfdan Mahler placed EPI at the center of the organization's primary health care strategy, framing immunization not as a specialty service but as a basic right of childhood. The practical obstacles were severe: vaccines required refrigeration along supply chains that often lacked reliable electricity, health workers needed training in reconstitution and injection technique, and many governments had no national immunization schedules at all. EPI's early years were spent building cold-chain infrastructure as much as delivering doses.
Coverage climbed steadily through the 1980s and 1990s, accelerating after the establishment of GAVI, the Global Alliance for Vaccines and Immunisation, in 2000. As EPI's platform matured, it carried additional antigens into national programs, including hepatitis B, Haemophilus influenzae type b, rotavirus, and pneumococcal conjugate vaccines. Each addition ran on logistics that EPI had built from scratch in the preceding decades.
A Lancet modelling study published in 2024 to mark EPI's 50th anniversary estimated that the program had averted roughly 154 million deaths over that period, with 101 million of those deaths in children under five. Measles vaccination alone accounted for approximately 60% of the total lives saved. No comparable intervention in the same timeframe approaches that scale of mortality reduction.
The program also shaped how countries think about health systems more broadly. National immunization days, surveillance networks for vaccine-preventable diseases, and the administrative infrastructure for tracking children through multi-dose schedules all trace directly to what EPI built. Polio eradication efforts, which have reduced wild poliovirus circulation to a handful of districts globally, run on the same operational backbone.
Key People
- Halfdan Mahler — WHO Director-General who made EPI a centerpiece of global primary health care.
- Ralph Henderson — WHO EPI director who led the program's operational expansion through the 1980s.
- Jonas Salk — Polio vaccine developer whose inactivated vaccine was an original EPI antigen.
Lancet, 2024 (50-year EPI modelling study)
Related landmarks
- 1976 · Nurses' Health Study (Public Health)
- 1968 · Oral Rehydration Therapy for cholera and diarrheal disease (Public Health)
- 1980 · Global Eradication of Smallpox (Public Health)
- 1964 · Surgeon General's Report on Smoking and Health (Public Health)