Standard of care for viral haemorrhagic fevers (VHFs): a systematic review of clinical management guidelines for high-priority VHFs av Rigby, I, Michelen, M, Dagens, A, Cheng, V, Dahmash, D, Harriss, E, Webb, E, Cai, E, Lipworth, S, Oti, A, Balan, V, Piotrowski, H, Nartowski, R, Rojek, A, Groves, H, Hart, P, Cevik, M, Bosa, HK, Blumberg, L, Fletcher, TE, Horby, PW, Jacob, ST, Sigfrid, L