1 Cochrane Airways, Population Health Research Institute, St George's, University of London, London, UK. Electronic address: [email protected].
2 Cochrane Airways, Population Health Research Institute, St George's, University of London, London, UK; British Medical Journal Technology Assessment Group (BMJ-TAG), London, UK.
3 Cochrane Airways, Population Health Research Institute, St George's, University of London, London, UK.
4 Division of Infection, Immunity and Respiratory Medicine, University of Manchester, Manchester, UK.