Received: 9 June 2021
Accepted: 15 November 2021
First Online: 2 December 2021
: The study was performed in accordance with the ethical standards of the Declaration of Helsinki (1964) and its subsequent amendments. Informed consent was obtained from all the parents and/or legal guardians of the infants included in the study. Ethical approval for this study was obtained from the Institutional Review Board of the Faculty of Health Sciences, University of Buea (IRB-FHS, UB). Administrative approval was obtained from the Regional Delegation of Public Health for the Southwest Region, and the directors of the health institutions included in the study. Confidentiality was ensured throughout the study.
: Not applicable.
: The authors declare that they have no competing interests.