Vi-specific serological correlates of protection for typhoid fever by Jin, C, Hill, J, Gunn, BM, Yu, W-H, Dahora, LC, Jones, E, Johnson, M, Gibani, MM, Spreng, RL, Alam, SM, Nebykova, A, Juel, HB, Dennison, SM, Seaton, KE, Fallon, JK, Tomaras, GD, Alter, G, Pollard, AJ