Innovative vaccine approaches-a Keystone Symposia report by Cable, J, Rappuoli, R, Klemm, EJ, Kang, G, Mutreja, A, Wright, GJ, Pizza, M, Castro, SA, Hoffmann, JP, Alter, G, Carfi, A, Pollard, AJ, Krammer, F, Gupta, RK, Wagner, CE, Machado, V, Modjarrad, K, Corey, L, B Gilbert, P, Dougan, G, Lurie, N, Bjorkman, PJ, Chiu, C, Nemes, E, Gordon, SB, Steer, AC, Rudel, T, Blish, CA, Sandberg, JT, Brennan, K, Klugman, KP, Stuart, LM, Madhi, SA, Karp, CL