Received: 16 January 2019
Accepted: 21 August 2019
First Online: 30 August 2019
Ethics approval and consent to participate
: Ethical approval was obtained from the Institutional Review Board of the Institute of Public Health, the University of Gondar and the ICF International Institutional Review Board. The data has been used only for this registered research and it could not be passed on to other researchers.
: Not applicable.
: The authors declare that they have no competing interests.