In what circumstances could non-daily pre-exposure prophylaxis for HIV substantially reduce program costs? - Mitchell, KM; Dimitrov, D; Hughes, J; Xia, F; Donnell, D; Amico, R; Bokock, K; CHITWARAKORN, A; Bekker, L-G; Holtz, T; Mannheimer, S; Grant, R; et al. (AIDS, 2018)