Received: 12 October 2018
Accepted: 26 December 2018
First Online: 8 January 2019
Ethics approval and consent to participate
: Ethical approval was granted by the National Health Service (NHS) Health Research Authority NRES Committee East of England, REC approval reference 13/EE/0157, IRAS 127675. Written informed consent was provided by parents/carers with verbal assent given by children.
: Not applicable: identifiable data from individual participants is not available. All participants have consented to the publication of anonymised data.
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