Funding for this research was provided by:
National Institute for Health Research (CDF-2016-09-014)
Received: 27 March 2018
Accepted: 2 May 2018
First Online: 8 May 2018
Ethics approval and consent to participate
: Ethical approvals have been received from the NHS Health Research Authority [17/LO/0872], the London Bridge Research Ethics Committee [17/LO/0872] and the LSHTM Observational Research Ethics Committee . Informed written consent will be obtained from each participant prior to enrolment and after information and an explanation of the study purpose and procedures is given.
: The authors declare that they have no competing interests.
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