Almost immediately, her data showed that the drone beat the car. Delivery times vary by distance, but drones consistently exceed typical driving times. Of the 12,733 orders over 32 months, the smallest difference was a 3-minute lift and the largest was 211 minutes, always in favor of the drone.

Drones also reduce the amount of expired and wasted blood. “I didn’t expect an immediate impact,” Nisingizwe said. “But we saw an immediate effect.” Those savings increased over time: Within 12 months, the drones reduced blood waste by 67 percent — a total of 140 reductions between 2017 and 2019.

“This is exciting for us,” said Israel Bimpe, a trained pharmacist and director of Zipline’s Rwanda-based African marketing department. “It’s a validation of what we’ve been doing, in many ways.” Since starting blood distribution in Rwanda, Zipline has also partnered with the government of Ghana in West Africa to deliver blood, medicines and vaccines by drone.

Drones appear to be filling a huge need, says Kathryn Maitland, a paediatrician at Imperial College London who was not involved in the study. Maitland has lived in East Africa for 22 years, where she conducts clinical trials for major diseases. For her, drones are especially useful for emergency blood transfusions. Children in East Africa are at risk of malaria, which can lead to severe anaemia. “They were often very sick,” she said. “If you need a blood transfusion, you need it now.” Traveling for a blood transfusion, however, takes time, which can put a sick child’s life at risk. And it’s expensive. “These things could be game-changers,” Maitland said of drone delivery. “The hard-to-reach places, of course.”

Thanks to drone deliveries, rural facilities can now order rarer blood products, including platelets, fresh frozen plasma, and cryoprecipitate — a special protein isolated from plasma. If these were out of stock locally, patients were previously referred to another hospital and transported by ambulance.

“Performance was better than expected,” said author and futurist Jonathan Ledgard, who helped advance the vision of medical drones in Africa. (Ledgard is a member of the Drone Industry Corporate Advisory Board.)

But the cost of those deliveries is an open question. In an emailed statement, Zipline’s senior vice president of external affairs, Anne Hilby, confirmed that the company and the Rwandan government have not disclosed cost details, adding that prices may vary based on customer needs. “Zipline offers a faster, more sustainable delivery method while remaining cost-competitive with traditional delivery and courier services,” she wrote.

Ledgard would like to see more transparency in the contract between Rwanda and Zipline. “I think taxpayers in these countries have to understand the real cost of it and what they’re getting out of it,” he said.

Nisingizwe didn’t analyze how much more Rwanda would pay to deliver blood using drones instead of cars, but she wants to look next. She also wants to know if drones are actually saving lives — something she wants to investigate later by analyzing whether urgent referrals to city hospitals have dropped, or whether serious outcomes like bleeding have dropped.