Ranking vaccines : a prioritization software tool. Phase II, Prototype of a decision-support system / Committee on Identifying and Prioritizing New Preventive Vaccines for Development, Phase II, Board on Population Health and Public Health Practice, Board on Global Health ; Guruprasad Madhavan, Kinpritma Sangha, Charles Phelps, Dennis Fryback, Rino Rappuoli, Rose Marie Martinez, and Lonnie King, editors ; Institute of Medicine of the National Academies