1. Division of Pulmonary, Critical Care, and Sleep Medicine, University of Connecticut School of Medicine , Farmington, Connecticut , USA
2. Department of Population Medicine, Harvard Medical School and Harvard Pilgrim Health Care Institute , Boston, Massachusetts , USA
3. Department of Medicine, Brigham and Women’s Hospital , Boston, Massachusetts , USA
4. Department of Medicine, Division of Infectious Diseases, University of Nebraska Medical Center , Omaha, Nebraska , USA