This metadata record records the existence of the interview transcripts, in accordance with LSHTM's Research Data Management policy and journal requirements. Participants gave written informed consent that their interview data could be used in papers. However, due to the age of the study they were not consulted on wider sharing of information. Interested parties wishing to access the transcripts should consult the authors listed in http://dx.doi.org/10.1186/s12913-016-1733-7 for further information.