WHO Immunization Program Saved 150 Million Lives and 10 Billion Years of Life

In 1974, the World Health Organization (WHO) launched the "Expanded Programme on Immunization (EPI)" to make lifesaving vaccines available to everyone worldwide.

To mark EPI's 50th anniversary, on May 2, 2024, THE LANCET published an analysis aiming to measure vaccination's global public health impact since the program began.

How Do Vaccines Work and Protect Against Disease?

Vaccines are biological preparations that train our immune system to protect against specific pathogens. A vaccine contains a small amount of weakened or inactivated pathogens, or their proteins. These stimulate the immune system to produce antibodies against the pathogen. If the vaccinated person encounters it again, the immune system quickly recognizes and destroys it, preventing disease.

Study Details

Researchers used mathematical and statistical models to estimate the global and regional public health effects of 50 years of vaccination against 14 pathogens covered by EPI.

The 14 pathogens were:

1. Corynebacterium diphtheriae bacteria - Diphtheria
2. Haemophilus influenzae type B bacteria - Meningitis and other invasive infections
3. Hepatitis B virus - Hepatitis B
4. Japanese encephalitis virus - Japanese encephalitis
5. Measles virus - Measles
6. Neisseria meningitidis A bacteria - Meningitis A
7. Bordetella pertussis bacteria - Whooping cough
8. Streptococcus pneumoniae bacteria - Invasive pneumococcal disease
9. Poliovirus - Polio (poliomyelitis)
10. Rotavirus - Rotavirus infections
11. Rubella virus - Rubella
12. Clostridium tetani bacteria - Tetanus
13. Mycobacterium tuberculosis bacteria - Tuberculosis
14. Yellow fever virus - Yellow fever

The models considered coverage of all routine and supplementary vaccinations against these pathogens since 1974. Mortality and morbidity averted in each age group were estimated against a hypothetical history without vaccination. The results were then used to estimate vaccination's contribution to declining infant and child death rates worldwide during this period.

150 Million Deaths Prevented

WHO's EPI vaccination program has prevented 154 million deaths since 1974: 

• 146 million were children younger than 5 
• 101 million were infants younger than 1

10 Billion Years of Life Gained

An average of 66 years of full health was gained for every death prevented, totaling 10.2 billion years of full health gained.

This highlights how vaccination programs not only reduce death rates but also help people live longer, healthier lives. In more detail:

1. An average of 66 years of full health was gained for every death prevented:

   • The research estimates that each death prevented through vaccination added an average of 66 years to a person's life. Vaccines therefore not only saved lives but also enabled long, healthy lives.
   • "Full health" means years lived in good health and free of disease.

2. This totals 10.2 billion years of full health gained:

   • The study states that vaccines saved 154 million lives. Multiplying these by an assumed average of 66 years of full health per life gives 154 million lives x 66 years = 10.2 billion years of full health.
   • This calculation illustrates vaccination programs' enormous contribution to global public health, both in saving lives and enabling longer, healthier lives.

Essential for Infant Health

Researchers suggest vaccination accounts for 40% of the observed global decline in infant deaths and 52% in the African region. In 2024, a child younger than 10 has a 40% greater chance of surviving to the next birthday than in a hypothetical history without vaccines. Increased survival probabilities are observed even at older ages.

The authors concluded that major childhood survival gains had been achieved in every global region since 1974. Over the past 50 years, EPI is estimated to have made the largest contribution to improved infant survival. In the context of stronger primary healthcare, the results show that equitable, universal access to immunization is vital to sustaining health gains and continuing to prevent avoidable infectious deaths.