Logic might dictate that unmanned drones could better deliver vaccines in developing countries when compared with ground-based transportation.Going over rather than through areas featuring rough roads, difficult terrain including mountains and jungles, and areas of unrest or open warfare would seem to represent the better choice.
Now a study by the Johns Hopkins Bloomberg School of Public Health and the Pittsburgh Supercomputing Center in Oakland published June 20 in the journal Vaccine concludes that drones could deliver vaccines more quickly and cheaply than ground-based transportation under a wide range of conditions.
Using the HERMES computer modeling program it developed, the team compared drone-based and ground-based vaccine delivery involving cars, trucks and motorcycles in one province of Mozambique.
At issue is the delivery of vaccines for hepatitis B, tetanus, measles and rotavirus, among others, with future use for potentially new vaccines such as those for dengue, malaria and Zika. Currently vials of vaccines are transported from one storage location to the next, eventually reaching centers where health workers can vaccinate patients. Most vaccines must be refrigerated to prevent spoilage.But the cost of ground-based distribution continues to rise, with increases jeopardizing immunization rates.
The study, however, shows that drone deliveries likely would be faster while saving 8 cents a dose with successful vaccination of 96 percent of the population rather than the current potential rate of 94 percent with ground transportation. What might sound like insignificant results actually represent sizable savings for low-income nations, with a 2 percent increase representing thousands and even millions of additional immunizations.
“Implementing an [unmanned aerial system] could increase vaccine availability and decrease costs in a wide range of settings and circumstances if the drones are used frequently enough to overcome the capital costs of installing and maintaining the system,” the study concludes. “Our computational model showed that the major drivers of cost savings from using the [drones] are road speed of traditional land vehicles, the number of people needing to be vaccinated, and the distance that needs to be traveled.”
Bruce Y. Lee, associate professor of international health at the Johns Hopkins Bloomberg School of Public Health and the study leader, said the Bill and Melinda Gates Foundation among other public-service foundations provided funding for the project, with the HERMES model providing “reasonably strong evidence” supporting the use of drone technology for distribution of vaccines.
But the results aren’t limited to the southern African country of Mozambique and other developing countries.
“We have to keep in mind that even in so-called high-income countries there are still low-income populations with poor access to health care,” Dr. Lee said. “If you look at the United States, there are many low-income populations with poorer access to health care than people in developing countries.” Those include Americans living in remote, rural and mountainous regions.
Leila Haidari, the supercomputing center’s public health applications manager and the study’s co-author, said the team set up complex virtual systems of vaccine distribution involving hubs, multiple refrigerator or cold storage systems for vaccines, numerous distribution routes and different means of transportation. It even involved virtual people independently going to different centers to receive vaccines.Multiple runs of the HERMES computer model focused on different scenarios, with each hub distributing vaccines over a radius of about 47 miles. Drones generally proved to be the more favorable method of vaccine delivery, Ms. Haidari said.
“This modeling is the key for decision support when you are looking at really complex systems like vaccine distribution because one change in one place can dramatically change the supply chain,” she said.
Bottom line, Dr. Lee said, is that the study shows that “the time is right to use computational modeling methods to address issues of public health.”
David Templeton: [email protected] or 412-263-1578.