Funding for this research was provided by:
the European Union's Seventh Framework Programme (305968)
Received: 2 July 2018
Accepted: 22 May 2019
First Online: 31 May 2019
Ethics approval and consent to participate
: This study received ethical approval from the Health Research and Ethics Committee of the University of Ibadan (UI/EC/13/0330).
: Not applicable.
: The authors declare that they have no competing interests.