1. Division of Pulmonary Rehabilitation, Istituti Clinici Scientifici Maugeri, IRCCS, Tradate, Department of Medicine and Surgery, Respiratory Diseases, University of Insubria, Varese-Como, Italy
2. Public Health Consulting Group, Lugano, Switzerland
3. Servizio di Epidemiologia Clinica delle Malattie Respiratorie, Istituti Clinici Scientifici Maugeri IRCCS, Tradate
4. Department of Infectious Diseases, Galliera Hospital, Genova, Italy
5. Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, Division of Infection, Royal London Hospital, Barts Health NHS Trust, London, UK