No matter what advanced method is used to develop and produce vaccines, their efficacy is limited by old technology – the refrigerator. All viral vaccines must either be stored frozen, or kept at low temperatures. If they are not properly stored, they lose potency and do not confer protection against infection. The decay of vaccine potency is a particular problem in underdeveloped regions that lack a continuous network of stable, refrigerated storage facilities – the ‘cold chain’. To solve this problem, the World Health Organization developed a portable kerosene-fired freezer to maintain the potency of oral poliovirus vaccine. A new method for drying vaccines could radically change the dependency of vaccines on the cold chain.