In 2024, the Expanded Programme on Immunization (EPI) is celebrating the 50th anniversary of its founding by the World Health Organization (WHO). The initiative—now commonly referred to as the Essential Programme on Immunization—was created to provide young children around the world with access to childhood vaccines, regardless of where they live, what their social status may be, or what their families’ economic standing is. Today, the EPI works to make vaccines accessible to children of all ages, as well as adolescents and adults.

With this anniversary in mind, several scientists used mathematical and statistical models in a study designed to estimate the effects that the EPI’s immunization work has had on public health. Their findings, published in early May 2024, found that EPI vaccination has prevented 154 million deaths worldwide. This includes 146 million children under 5 years old. Notably, most of those whose lives were saved due to vaccination were infants (101 million total).

“As a result of 50 years of vaccination, a child born today has a 40% increase in survival for each year of infancy and childhood,” the study authors wrote.

The vaccines offered by the EPI provide protection against a wide range of pathogens, which are organisms that cause infectious diseases. As of this year, EPI vaccines help protect people against 14 pathogens, including diphtheria, Haemophilus influenzae type B, hepatitis B, Japanese encephalitis, measles, meningitis A, pertussis, invasive pneumococcal disease, polio, rotavirus, rubella, tetanus, tuberculosis and yellow fever.

Of all the EPI vaccines that scientists evaluated in the study, the vaccine for measles proved to have the greatest impact on increasing the chances of infant survival, making up 60% of the lives saved due to vaccination. However, 33 million children worldwide missed a dose of their measles vaccine in 2022. That year, global cases of measles increased by 18% compared to 2021, with deaths increasing by 43%.

Tracking the impact of flu vaccines on flu burden in the U.S.

According to the published study, the EPI initiative expanded its vaccine coverage this year to include influenza vaccination. (As mentioned earlier, the EPI initiative offers a vaccine for Haemophilus influenzae; however, this bacterial pathogen does not cause the flu.) Because of this, none of the study data reflects how flu vaccines have affected survival from the flu worldwide.

However, for many years, the Centers for Disease Control and Prevention (CDC) have tracked the effects of vaccination on preventing flu burden—the burden that influenza causes to Americans through flu-related illnesses, medical visits, hospitalizations and deaths. The CDC also estimates the burden that the seasonal flu causes each year.

The estimates created by the CDC for flu burden and flu burden reduction  will change depending on the data for each flu season on the  which flu viruses are circulating, vaccine coverage (percentage of the population that has been vaccinated that season) and vaccine effectiveness.

Between 2010 and 2022, for example, the numbers of people whose lives have been saved by flu vaccines in the United States have spanned a wide range. In the 2013–2014 flu season, CDC estimates that 12,000 lives were saved due to seasonal flu vaccination. By comparison, during the 2021–2022 flu season—when the flu was less widespread due to masking, reduced travel, physical distancing and other measures that were taken by people to limit the spread of COVID-19—the CDC estimates that 1,100 lives were saved in the due to flu shots.

All in all, between 2010 and 2022 in the United States, estimates indicate that 366,900 people died due to the flu, and that flu vaccines saved the lives of approximately 64,000 people. If the number of lives saved due to flu vaccines seems relatively low, consider that during that same 12-year period, the rates of flu vaccination to all eligible people aged 6 months and older has never risen above 52.1%. The national goal for flu vaccination—which is part of the U.S. government’s Healthy People 2030 public health initiative which aims to help people achieve “well-being free of preventable diseases”—is to have 70% of all eligible people vaccinated for the flu each season.

Regardless, the value that flu vaccines—and vaccines for other infectious diseases—provide in helping to increase survival is clear.

“Vaccines are among the most powerful inventions in history, making once-feared diseases preventable,” noted Dr. Tedros Adhanom Ghebreyesus, director general of the WHO, when publication of the EPI study was announced in April. “Thanks to vaccines, smallpox has been eradicated, polio is on the brink, and with the more recent development of vaccines against diseases like malaria and cervical cancer, we are pushing back the frontiers of disease. With continued research, investment and collaboration, we can save millions more lives today and in the next 50 years.”

Read more about the impact that vaccines have made over the last 50 years through the EPI