1. From the Section of Internal Medicine, King Faisal Specialists Hospital and Research Centre, Riyadh, Saudi Arabia
2. From the Section of Infectious Diseases, Department of Medicine, King Faisal Specialists Hospital and Research Centre, Riyadh, Saudi Arabia
3. From the Department of Biostatistics, Epidemiology and Scientific Computing, King Faisal Specialists Hospital and Research Centre, Riyadh, Saudi Arabia