A consultant in pulmonary medicine and an intensivist at the Zuckerberg San Francisco General Hospital, John has expertise in critical care and respiratory infectious diseases, with a particular interest in HIV-associated highly drug-resistant tuberculosis clinical management and translational research. He has specialized training in epidemiology, statistical prediction, diagnostic test evaluation, and randomized clinical trials; leads a Fogarty biomedical research training program (NIH D43) at the University of Zimbabwe; and is Chair of an AIDS Clinical Trials Group phase II/III adaptive RCT evaluating novel regimens for TB treatment shortening. He is also on the Editorial Board of PLoS Medicine, where he is Editor for Respiratory Medicine.