Optimising DTwP-containing vaccine infant immunisation schedules (OptImms) — a protocol for two parallel, open-label, randomised controlled trials by Kelly, S, Liu, X, Theiss-Nyland, K, Voysey, M, Murphy, S, Li, G, Nyantaro, M, Gurung, M, Basnet, S, Pokhrel, B, Bijukchhe, SM, Eordogh, A, Gombe, B, Kakande, A, Kerridge, S, Kimbugwe, G, Kusemererwa, S, Lubyayi, L, Luzze, H, Mazur, O, Mujadidi, YF, Nabukenya, S, Nagumo, W-R, Nareeba, T, Noristani, R, O'Reilly, P, Roberts, A, Shah, G, Shrestha, S, Shrestha, LP, Thapa, SB, Kibengo, FM, Sharma, AK, Elliott, A, Shrestha, S, Pollard, AJ