1. Yaoundé Central Hospital, P.O. Box 31186, Yaoundé, Cameroon
2. Research, Education and Health Development Associates Group (REHDAG), Dschang, Cameroon
3. Ministry of Public Health, Yaoundé, Cameroon
4. Faculty of Medicine and Biomedical Sciences, University of Yaoundé I, P.O. Box 1364, Yaoundé, Cameroon
5. Institute for Training and Demographic Research, P.O. Box 5644, Yaoundé, Cameroon
6. Yaoundé Central Hospital, Blood Bank Unit, P.O. Box 31186, Yaoundé, Cameroon