ADS is funded by an NIHR Academic Clinical Lectureship. AB is an NIHR
Senior Investigator and additionally was supported by the NIHR Respiratory Disease.
RH was supported by the National Institute for Health Research (NIHR) Collaboration
for Leadership in Applied Health Research (CLAHRC) North Thames at Barts NHS
Trust. The views expressed are those of the author(s) and not necessarily those of
the NHS, NIHR or Department of Health