Building on the momentum of the smallpox eradication effort, the Expanded Programme on Immunization (EPI) was launched in 1974 to ensure that all children, in all countries, benefited from life-saving vaccines. This programme has evolved into what is now commonly known as the Essential Programme on Immunization.

Today every country in the world has a national immunization programme and vaccines are viewed as one of the safest, most cost-effective, and successful public health interventions to prevent deaths and improve lives. Since the initial focus on protection against seven childhood vaccine-preventable diseases ( Bacillus Calmette-Guérin (BCG), diphtheria, measles, pertussis, polio, smallpox, and tetanus) over five decades ago, the addition of new vaccines has increased the breadth of protection provided by immunization, to include vaccinations for protection of older children, adolescents and adults.

As of 2026, there are now 14 vaccine-preventable diseases with recommendations by WHO for all countries to include in the EPI programme. They are: diphtheria, Haemophilus influenzae type B (Hib), Hepatitis B (HepB), human papillomavirus (HPV), measles, pertussis, pneumococcal disease, polio, Respiratory Syncytial Virus (RSV), rotavirus, rubella, tetanus, and, for high-risk groups, COVID-19 and seasonal influenza.  In addition, there are more than 20 context specific vaccine-preventable diseases, for particular geographic areas or populations, and/or taking into account specific prerequisites or flexibilities of the immunization programme.

2024 marked 50 years since the Expanded Programme on Immunization (EPI) was initiated. In these 50 years alone, vaccines have saved the lives of 154 million people.