Deployment of vaccine cold chain equipment in resource-limited settings: lessons from the Gavi Cold Chain Optimization Platform in Cameroon by Nkwain, J, Zambou, VM, Nchinjoh, SC, Agbor, VN, Adidja, A, Mbanga, C, Edwidge, NN, Ndoula, ST, Ateke Njoh, A, Diack, D, Di Mattei, P, Wiwa, O, Diaby, O, Saidu, Y