New York: Using unmanned drones to deliver vaccines in low- and middle-income countries may save money and improve vaccination rates, says a study. The cost savings would come from drones being able to deliver vaccines more quickly and cheaply than land-based methods limited by road conditions and the need for costly fuel and maintenance, the researchers noted. "Many low- and middle-income countries are struggling to get lifesaving vaccines to people to keep them from getting sick or dying from preventable diseases," said senior author Bruce Lee, Associate Professor at Johns Hopkins Bloomberg School of Public Health in Baltimore, Maryland, US. "You make all these vaccines but they're of no value if we don't get them to the people who need them. So, there is an urgent need to find new, cost-effective ways to do this," he noted. Non-vaccine costs of routine immunizations are expected to rise by 80 percent between 2010 and 2020, with more than one-third of costs attributable to supply chain logistics. Supply chain inefficiencies can mean that many vaccines don't even reach the people who need them. For their study, Lee and his colleagues created a HERMES computer model to simulate a traditional land-based transportation system - a combination of trucks, motorbikes, and public transit - and compared it with an unmanned drone system for delivering vaccines as part of an immunisation programme. Seattle-based non-governmental organization Village Reach helped provide data for the model. They varied characteristics such as geography, population, road conditions and vaccine schedule in order to assess which conditions would most contribute to drones offering the biggest cost savings. They found that using drones to get vaccines to the last stop on their journey - vaccination locations - could slightly improve vaccine availability - potentially immunizing 96 percent of the target population as compared to 94 percent using land-based transport - while producing roughly 20 percent savings. The study was published in the journal Vaccine. Drones are currently being tested for medical supply deliveries in rural Virginia, Bhutan and Papua New Guinea, a Johns Hopkins School of Public Health statement said. UNICEF is testing the feasibility of using them to transport lab samples in Malawi. And in Tanzania, there are efforts afoot to transport blood and essential medications, the statement added.