1 Institute for Global Health and Infectious Diseases, The University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina, USA weiming_tang@med.unc.edu.
2 Lawson Unit, University Hospitals Sussex NHS Foundation Trust, Brighton, UK.
3 Department of Infectious, Tropical Diseases and Acquired Immunodeficiency, Pomeranian Medical University in Szczecin, Szczecin, Poland.
4 Institute for Global Health, University College London, London, UK.