The expanding vaccine development pipeline, 1995-2008.

Successful launches of recently licensed vaccines contrast with pharmaceutical industry concerns about unfavorable market conditions, making the status and future of vaccine development uncertain. We assessed trends in private-sector vaccine research and development for the period 1995-2008, using a global pharmaceutical database to identify prophylactic vaccines in preclinical, Phase I, Phase II, or Phase III stages of development. We counted companies that research and/or manufacture vaccines ("vaccine originators") and their vaccine products in each year.