Six years ago, Rwanda had a blood delivery problem. More than 12 million people live in the small East African country, and like those in other nations, sometimes they get into car accidents. New mothers hemorrhage. Anemic children need urgent transfusions. You can’t predict these emergencies. They just happen. And when they do, the red stuff stored in Place A has to find its way to a patient in Place B—fast.

That’s not a huge problem if you live in a city. In the United States and the United Kingdom, 80 percent of the population clusters around urban hubs with high-traffic hospitals and blood banks. In African nations like Libya, Djibouti, and Gabon, about 80 to 90 percent of the populations live in cities, too. But in Rwanda, that number flips: 83 percent of Rwandans live in rural areas. So, traditionally, when remote hospitals needed blood, it came by road.

That’s not ideal. The country is mountainous. Roads can be hot, long, and bumpy. If kept cool, donated blood can be stored for just a month or so, but some components that hospitals isolate for transfusions—like platelets—will spoil in days. A turbulent drive is not a perfect match for such finicky cargo.

That logistics issue historically incentivized rural facilities to order more blood than they needed. “There was a problem of overstocking,” says Marie Paul Nisingizwe, a PhD candidate in Population and Public Health at the University of British Columbia, who focuses her research on Rwanda, her home country. Stocking a little extra could save time later. But if a low-traffic facility didn’t wind up using the blood before it expired, they’d have to dump it.

In 2016, Rwanda’s government signed a contract with Zipline, a San Francisco-based drone startup, to streamline blood deliveries. Zipline’s autonomous drones would fly the blood from a distribution hub to the health care facility. The blood, contained within an IV bag, would parachute down in an insulated cardboard box, and the drone would zip back. Today, Zipline has two hubs in Rwanda; each can make up to 500 deliveries per day.

And now for the first time, there’s proof that drone blood services improve delivery speed and reduce waste. Writing in the April issue of Lancet Global Health, Nisingizwe analyzed nearly 13,000 drone orders between 2017 and 2019 and found that half of the orders took 41 minutes or less to deliver by drone. On the road, that median time would be at least two hours. Reports of wasted blood donations dropped.

The study is the first to analyze medical delivery drones in Africa. (Drone programs are more common in higher-income countries, where they are used to deliver medicine and defibrillators.) “It’s amazing to see that actually the delivery drone is feasible in African settings,” says Nisingizwe. (Her research team is not affiliated with Zipline.)

“It’s so good. And it’s not just good for Rwanda,” says Timothy Amukele, a pathologist who is not involved with the research team or Zipline, but who previously ran a medical drone group with projects in Namibia and Uganda. (Amukele is currently the global medical director for ICON Laboratory Services, which helps run clinical trials.) Drone applications for global medicine have been touted for years, but researchers have lacked concrete data to back up that promise, says Amukele: “This is more than just guys playing with toys.”

“Drones are not easy,” he continues. “To actually make this a success, where they’re getting blood and packing it safely and releasing the drones and monitoring the flight and bringing them back—and for five years covering 80 percent of that country—it’s just really impressive.”

Don’t be fooled by Rwanda’s rural demographics; the country has a reputation for leaning into health tech innovations. Rwanda’s universal health care system reaches over 90 percent of the population. In 2009, the government piloted a phone-based program, called RapidSMS, to track and reduce maternal and child mortality. By 2013, RapidSMS connected 15,000 villages to the country’s wider network of doctors, hospitals, and ambulances.

“They have one of the most complete electronic data systems,” says Michael Law, Nisingizwe’s adviser and a health policy researcher at UBC, which lets Rwanda’s Ministry of Health track how many people see physicians, how many have malaria or HIV, and how many give birth at health facilities. That’s a gold mine for researchers like Nisingizwe, who want to measure just how much innovation helps. “Frankly, we couldn’t have done this evaluation had they not had the data system in place,” says Law.