From the aInternational Antiviral Therapy Evaluation Center, Academic Medical Center, Amsterdam, the Netherlands, bHospital Pitié Salpêtrière, Paris, France, cNorthwestern University Medical School, Chicago, Illinois,, USA, dRand Schrader Clinic, LAC and USC Medical Center, Los Angeles, USA, eHospital Clinic Provincial, Barcelona, Spain, fCentrum Diagnostyki i Therapii, Warsaw, Poland, gGermans Trias I Pujol, Badalona, Spain, hGoethe University Frankfurt, Germany, iJvGoyen Amsterdam, the Netherlands, jCHU Saint-Pierre, Brussels, Belgium, kUniversity Hospital, Milan, Italy, lUniversity of Utah, Salt Lake City, Utah, USA, mMedizinische Hochschule Hanover, Zentrum Innere Medizin und Dermatologie, Hanover, Germany, nInstituto de Salut Carlos III, Madrid, Spain, oSt Paul's Hospital, Vancouver, British Columbia, Canada, pFaculdade de Medicina, Lisbon, Portugal, qWeill Medical College of Cornell University, New York, USA, rSt. Laszlo Hospital, Budapest, Hungary, sUniversity of Alabama, Birmingham, Alabama, USA, tDepartment of Infectious Diseases, Tropical Medicine and AIDS, Academic Medical Center, Amsterdam, the Netherlands. *See Appendix for study sites and other members.