1. Department of Epidemiology, University of Colorado, Anschutz Medical Campus, Aurora, Colorado, USA
2. Department of Ophthalmology, University of Colorado, Anschutz Medical Campus, Aurora, Colorado, USA
3. Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
4. Division of Infectious Diseases, Northwestern University, Feinberg School of Medicine, Chicago, Illinois, USA
5. Department of Infectious Diseases and Microbiology, School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
6. Department of Epidemiology, Fielding School of Public Health, UCLA, Los Angeles, California, USA
7. Department of Medicine, Division of General Internal Medicine, Georgetown University, Washington, DC, USA