Funding for this research was provided by:
Wellcome Trust (096919)
National Institute for Health Research (HPRU-2012-10076)
Rosetrees Trust (BH154239)
Received: 6 March 2019
Accepted: 5 June 2019
First Online: 15 June 2019
Ethics approval and consent to participate
: Not applicable.
: All authors have read and agreed to the final version of the manuscript.
: The authors declare that they have no competing interests.