1. Department of Epidemiology, School of Public Health, University of Alabama at Birmingham, Birmingham, Alabama , USA
2. Division of Epidemiologic Research, Department of Research and Evaluation, Kaiser Permanente Southern California, Pasadena, California , USA
3. Division of Research, Kaiser Permanente Northern California , Oakland, California , USA
4. Department of Infectious Diseases, Oakland Medical Center, Kaiser Permanente Northern California , Oakland, California , USA
5. Department of Infectious Diseases, South Bay Medical Center, Kaiser Permanente Southern California , Harbor City, California , USA
6. Department of Clinical Science, Kaiser Permanente Bernard J. Tyson School of Medicine , Pasadena, California , USA
7. Department of Health Systems Science, Kaiser Permanente Bernard J. Tyson School of Medicine , Pasadena, California , USA