The spores themselves will therefore act as the vaccine. Sonenshein is one of the winners of Grand Challenge No. 2: “Prepare vaccines that do not require refrigeration.” If his idea works it would, as a bonus, meet challenge No. 3: “develop needle-free delivery systems for vaccines,” since people would get vaccinated by drinking water laced with the spores. The actual winners of challenge No. 3, though, all have variants of the same idea.This is to make what is, in essence, vaccine snuff. Three of these winners cannot resist modish use of the “n” prefix in their proposals. David Edwards, of Harvard, proposes nasal sprays containing “nanoparticle aerosols” made of vaccine. James Baker, of the University of Michigan, prefers “nanoemulsions” that can be administered as nose drops. Meanwhile, Maria Alonso, of the University of Santiago de Compostela, in Spain, opts for “surfacemodified nanostructures.” But she, Edwards, Baker and, indeed, the other two winners have a common design. This is to produce something that will be absorbed by the mucous membranes of the respiratory tract. In some cases the goal is not merely to use mucous membranes as entry points, but also to stimulate an immune response in them directly. Existing vaccines work by stimulating bits of the immune system that work in the blood and the lymph. But soft, moist membranes are particularly vulnerable to bacteria and viruses, and have their own immune responses which might be recruited by a suitably designed vaccine. There is even a plan for a hand-held diagnostic system, shades of Dr. McCoy in “Star Trek.” This idea, proposed by Paul Yager of the University of Washington, would take a drop of blood and run it over a card covered with chemicals that react characteristically with molecules produced by particular diseases. How many of these ideas will translate into lives saved is, of course, impossible to say―and that is not only because of uncertainties about which of them will work. As the quest to deliver antiretroviral drugs to poor people with AIDS shows, implementation is everything. Such drugs have been available for almost a decade, but only a small number of those who need them receive them. The Grand Challenge winners differ from antiretrovirals in that they are being developed specifically for use in poor countries. But thinking now about how they will be delivered is just as important as getting the science right.