Heterologous two-dose vaccination with simian adenovirus and poxvirus vectors elicits long-lasting cellular immunity to influenza virus A in healthy adults by Coughlan, L, Sridhar, S, Payne, R, Edmans, E, Milicic, A, Venkatraman, N, Lugonja, B, Clifton, L, Qi, C, McMichael, A, Folegatti, PM, Lawrie, AM, Roberts, R, de Graaf, H, Sukhtankar, P, Faust, SN, Lewis, DJM, Lambe, T, Hill, AVS, Gilbert, SC