Modification - We started the Gates Foundation 25 years ago to save and improve children’s lives. But no one can solve a problem they don’t fully understand. And back in 2000, the world’s understanding of childhood mortality was occasionally inaccurate, often imprecise, and almost always incomplete.
That’s why I believe the breakthrough that transformed our foundation in the two-and-a-half decades since wasn’t a single vaccine or treatment—it was a revolution in the world’s understanding of childhood mortality. Through advances in how researchers collect and analyze global health data, we now know much more about what kills children, where these deaths occur, and why some kids are more vulnerable than others. By putting those insights to work, we’ve been able to save lives.
The first challenge was knowing exactly what was killing children.
Reading the 1993 World Development Report opened my eyes to the scale of the problem: Around 12 million children under the age of five were dying every year, with a staggering disparity between rich and poor countries. But the available data was fragmented and inconsistent. That made it difficult to understand trends or allocate resources effectively.
So the foundation helped create the Institute for Health Metrics and Evaluation at the University of Washington, to give a permanent home to the Global Burden of Disease study—originally developed in the 1990s by researchers at Harvard University and the World Health Organization. We wanted to expand it from a static snapshot of the problem into a regularly updated tool that tracked how diseases impact people around the world. That gave us something the world never had before: a comprehensive—and current—picture of child mortality across every country.
Measuring symptom-based causes of children’s deaths was an important step. But broad disease categories like “diarrhea” or “respiratory infection” didn’t give us enough information to act on. We needed to know which specific pathogens were responsible for the most common and fatal cases. So the Gates Foundation funded two landmark studies to find out.
In 2013, the Global Enteric Multicenter Study, or GEMS, found that rotavirus was causing 20 percent of lethal diarrhea cases in kids. At the time, diarrhea was the second-leading infectious killer of children. While oral rehydration therapy had already helped bring down deaths over previous decades, GEMS helped fast-track the rollout of a more targeted tool—a new rotavirus vaccine—in the hardest-hit countries, in close partnership with Gavi, the Vaccine Alliance.
A year later, the Pneumonia Etiology Research for Child Health study, or PERCH, revealed that respiratory syncytial virus, or RSV, was a much more common cause of severe pneumonia—the leading infectious killer of kids around the world—than previously understood. (And not just in low- and middle-income countries, where 97 percent of RSV deaths occur, but in higher-income ones too, where the virus still fills pediatric hospital wards each winter.) That prompted us to expand our investments in RSV prevention, which led to the approval of the first maternal vaccines for RSV in 2023.
But understanding what causes childhood mortality wasn’t enough on its own, because deaths aren’t distributed evenly across countries—or even within them. That’s why our second challenge was to figure out where exactly children were dying.
At the time, most health data was collected at national or regional levels. That masked major differences in disease burden from one community to the next—and made it harder to target interventions effectively.
To solve this second challenge, the foundation invested in new approaches to health mapping that combined satellite imagery, GIS technology, GPS data, and local health surveys. These maps gave Ministries of Health and implementing partners unprecedented, anonymized detail about disease patterns and population distribution, down to individual neighborhoods, that transformed how and where public health resources are deployed—while still preserving the privacy of the individual children and families in these places.
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