At 10 cents per polio vaccine, there are still places where administering them is non-negligible because it's not the cost of the test itself that's an issue. Granted, this probably isn't good enough to make a difference, but if you could get tested just with a cell phone with Internet access without needing to physically ship anything not need a medical professional at the site, it probably could make a big difference in some areas. Granted, those are places where getting medical treatment afterwards is probably hard but at least dealing with it via dietary choice, when that luxury is an option, may help.