Funding for this research was provided by:
Bill and Melinda Gates Foundation (OPP1066200, OPP1066203)
Received: 23 June 2020
Accepted: 15 October 2020
First Online: 30 October 2020
Ethics approval and consent to participate
: This study was approved the Ethical Review Committee of Aga Khan University in Karachi, Pakistan (informed consent obtained from parents and/ or guardians).
: Not applicable.
: The authors declare that they have no competing interests.