Funding for this research was provided by:
Parthenon Trust (n/a)
Medical Research Council (n/a)
Received: 10 October 2018
Accepted: 25 November 2019
First Online: 18 December 2019
Ethics approval and consent to participate
: The Holdsworth Memorial Hospital Ethics Committee gave approval for the study; informed written consent from parents and assent from children were obtained.
: Not applicable
: The authors declare that they have no competing interests.