Funding for this research was provided by:
Medical Research Council
Article History
Received: 11 June 2019
Accepted: 31 October 2019
First Online: 21 November 2019
Ethics approval and consent to participate
: Ethical approval was granted by the National Health Service (REC: 13/EE/0157). Parents/caregivers provided written consent and child verbal assent was obtained.
: Not applicable. Identifiable data from individual participants is not available. All participants have consented to the publication of anonymised data.
: The authors declare that they have no competing interests.