By 2020, vaccination initiatives in developing nations will have prevented 20 million deaths and saved a whopping $350 billion in health-care costs, a new study has found.

Conducted by the University of North Carolina at Chapel Hill (UNC), a team of researchers analyzed the impact of Gavi, a global vaccine initiative launched in 2000 to provide vaccines to children in the world’s poorest countries.

Funded by organizations like the World Health Organization (WHO) and the Bill & Melinda Gates Foundation, donations have contributed to the immunization of 580 million children across the 73 countries that the team examined.

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“Vaccination is generally regarded to be one of the most cost-effective interventions in public health,” Sachiko Ozawa, an associate professor of the UNC Eshelman School of Pharmacy, said in a press release.

“Decision makers need to appreciate the full potential [of] economic benefits that are likely to result from the introduction and sustained use of any vaccine or vaccination program,” Ozawa added.

The broader economic savings, researchers estimate, total $820 billion.

Read More: Study: Vaccines Have Prevented 450,000 Deaths in US Since 1963

The use of just 10 vaccines — including hepatitis B, human papillomavirus, measles, and yellow fever — have also prevented around 500 million illnesses and 9 million cases of long-term disabilities.

Without proper vaccination availability, measles and mumps outbreaks could become more common, researchers say.

In 2014, the United States experienced a record number of measles cases at 667. The majority of people who got measles were unvaccinated, the Center for Disease Control and Prevention found.

Read More: Vaccines Are So Clearly Effective, Even Congress Agrees They Are Safe

“It is ironic that in the anti-vaccination community, the very people who are denying protection to their children by foregoing vaccination are healthy and alive today because they, and possibly their parents, were vaccinated,” S. Jay Olshansky, professor of epidemiology and biostatistics at the University of Illinois, said earlier this year in a press release.

Today, around the rest of the world, 1.4 million children under age 5 are still endangered by diseases in regions where vaccines may not be as readily available as they are in the US. Although vaccination initiatives like Gavi have made huge strides in worldwide vaccination, efforts towards ending epidemics are all but over.