Funding for this research was provided by:
National Institute for Health Research
Received: 28 October 2019
Accepted: 24 June 2020
First Online: 1 July 2020
Ethics approval and consent to participate
: The study was approved by the Health Research Authority NHS Research Ethics Committee (Reference: 16/WA/0241) as well as the London School of Hygiene & Tropical Medicine ethics committee (Reference: 11628).
: Participant consent was not obtained due to the de-identified nature of the data.
: The authors declare they have no competing interest.