1. Department of Cardiovascular Sciences, University of Leicester, Leicester, UK
2. Department of Respiratory Sciences, University of Leicester, Leicester, UK
3. Department of Infectious Diseases and HIV Medicine, Leicester Royal Infirmary, University Hospitals of Leicester NHS Trust, Leicester, UK
4. Department of Geriatric Medicine, Leicester Royal Infirmary, University Hospitals of Leicester NHS Trust, Leicester, UK
5. Department of Virology, Leicester Royal Infirmary, Leicester Royal Infirmary, University Hospitals of Leicester NHS Trust, Leicester, UK