1. Section of Pulmonary and Critical Care Medicine, Department of Medicine, The Aga Khan University, Karachi, Pakistan
2. Section of Infectious Diseases, Department of Medicine, The Aga Khan University, Karachi, Pakistan
3. Department of Pathology and Laboratory Medicine, The Aga Khan University, Karachi, Pakistan
4. Department of Pathology and Laboratory Medicine, The Aga Khan University, Stadium Road, P.O. Box 3500, Karachi 74800, Pakistan