Stanley A Plotkin1, Adel A F Mahmoud, Jeremy Farrar. 1. From the Department of Pediatrics, University of Pennsylvania, Philadelphia (S.A.P.); the Foundation for Vaccine Research, Washington, DC (S.A.P., A.A.F.M.); the Department of Molecular Biology and the Woodrow Wilson School of Public and International Affairs, Princeton University, Princeton, NJ (A.A.F.M.); and the Wellcome Trust, London (J.F.).