1. Division of Biostatistics, University of Minnesota, Minneapolis, MN, USA
2. CICAL and Hospital Italiano de Buenos Aires, Buenos Aires, Argentina
3. Washington Veterans Affairs Medical Center, Washington, DC, USA
4. Medical Research Council Clinical Trials Unit, University College London, London, UK
5. The Kirby Institute, University of New South Wales, Sydney, NSW, Australia
6. Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
7. National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA