Funding for this research was provided by:
Health Services Research Programme (13/54/25)
Received: 15 March 2019
Accepted: 7 November 2019
First Online: 21 November 2019
Ethics approval and consent to participate
: The study was approved by the London School of Hygiene & Tropical Medicine (Ref 10107) and NHS (REC 15/LO/1135) research ethics committees.Participants aged 16–21, and parents/carers of 13–15 year olds gave written informed consent to participate. Participants aged 13–15 additionally gave their written informed assent.
: Participants consented for anonymised quotations from their interviews to appear in publications.
: The authors declare that they have no competing interests.