1 Statistics Sierra Leone, Tower Hill, Freetown, Sierra Leone; College of Medicine and Allied Health Sciences, University of Sierra Leone, New England, Freetown, Sierra Leone; School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa. Electronic address: osman.sankoh@statistics.sl.
2 College of Medicine and Allied Health Sciences, University of Sierra Leone, New England, Freetown, Sierra Leone; Sustainable Health, Freetown, Sierra Leone.