Immunization programmes, having made significant progress in protecting over 80% of the world's children against six vaccine-preventable diseases, are now facing a crisis in funding for their vaccine supply. Contributing to this situation are changing donor priorities, rising prices, increased needs for vaccines for new disease control initiatives, and the availability of costly new or improved vaccines. The Task Force on Situation Analysis for Vaccine Supply (TFSA) of the Children's Vaccine initiative (CVI) has developed a framework which provides a logical division of countries into groups that might share similar vaccine supply systems. This framework provides a basis on which to analyse the needs and potential solutions for vaccine supply in countries based on their populations, national wealth, and current ability to produce vaccine. This framework has facilitated the development of strategies to strengthen national vaccine supply systems. it has also provided guidance for governments, donor's and development agencies on tire most appropriate actions for assuring the objective of sustainable vaccine supply.