One of finalists of the Gates Foundation Grand Challenge competition is this team, which is working on doing the following:

Optimizing Immunization Systems: Delivering Vaccines with Unmanned Aerial Vehicles

George Barbastathis and collaborators at the Harvard-MIT Division of Health Sciences and Technology in the U.S. are developing unmanned aerial vehicles that can be deployed by health care workers via cell phones to swiftly deliver vaccines to hard-to-reach locations.