This commentary discusses the barrier of vaccine price on sustainable immunization programs in developing countries and offers examples of new mechanisms driven by public-private partnerships to overcome issues of affordability. These mechanisms include Advance Market Commitments with vaccine manufacturers, which take a demand-pull approach to ensure increased production of available vaccines or development of new vaccines for neglected diseases. A second approach applies a supply-push mechanism, such as technology transfer to developing-country manufacturers. A public-private partnership that set long-term, maximum public-sector pricing to increase access of a Japanese encephalitis vaccine for the developing world is highlighted. Lessons learned from this experience can be applied to address common obstacles to new vaccine introduction in resource-limited countries, including issues of affordability, manufacturing capacity, equity in access and quality assurance.