aDivision of HIV, Infectious Diseases and Global Medicine, Zuckerberg San Francisco General Hospital and Trauma Center, University of California, San Francisco, San Francisco, California

bDepartment of Population Health Sciences, Duke University School of Medicine, Durham, North Carolina

cDivision of Infectious Diseases, Washington University School of Medicine, St. Louis, Missouri, USA

Correspondence to Andrew D. Kerkhoff, MD, PhD, MSc, Division of HIV, Infectious Diseases and Global Medicine, Zuckerberg San Francisco General Hospital and Trauma Center, Department of Medicine, University of California San Francisco School of Medicine, 1001 Potrero Avenue, 409 San Francisco, CA 94110, USA. Tel: +1 415 476 1528; e-mail: [email protected]