...and that's why I've been terrified of bioterrorism. your plan is simple and elegant and horrifying. making such viruses is getting easier every day. eventually it will be easy enough that some crank will do something like this. Jesus..
we should increase funding for developing pathogen sensors, and put them in public transportation hubs. eventually we'll probably start requiring saliva or nasal swabs from randomly-selected travelers. it sucks but I don't see a better way..