Efficiency of transplacental transfer of respiratory syncytial virus (RSV) specific antibodies among pregnant women in Kenya by Nyiro, JU, Bukusi, E, Mwaengo, D, Nyaguara, A, Nyawanda, B, Otieno, N, Bigogo, G, Murunga, N, Widdowson, M-A, Verani, JR, Chaves, SS, Mwangudza, H, Odundo, C, Berkley, JA, Nokes, DJ, Munywoki, PK