1. Acute Communicable Disease Control Unit, Los Angeles County Department of Public Health, Los Angeles, California, USA
2. Infectious Disease Clinical Outcomes Research Unit, Division of Infectious Disease, Los Angeles Biomedical Research Institute, Harbor-UCLA Medical Center, Torrance, California, USA
3. David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California, USA
4. University of Southern California, Los Angeles, California, USA