1 Department of Respiratory Sciences, University of Leicester, Leicester LE1 7RH, UK; Department of Infectious Diseases and HIV Medicine, Leicester Royal Infirmary, University of Leicester Hospitals NHS Trust, Leicester, UK.
2 Department of Cardiovascular Sciences, University of Leicester, Leicester LE1 7RH, UK.
3 Department of Respiratory Sciences, University of Leicester, Leicester LE1 7RH, UK; Department of Infectious Diseases and HIV Medicine, Leicester Royal Infirmary, University of Leicester Hospitals NHS Trust, Leicester, UK. Electronic address: mp426@le.ac.uk.