Funding for this research was provided by:
Bill and Melinda Gates Foundation
Global Fund to Fight AIDS, Tuberculosis and Malaria
Received: 6 September 2021
Accepted: 30 November 2021
First Online: 20 December 2021
: Not applicable.
: No study participants were involved and thus no informed consent was required.
: KAL, LXH, AT, GG and PA are current or former staff members of the World Health Organization and are responsible for the views expressed in this publication, which do not necessarily represent the decisions or policies of the WHO. The authors declare they have no competing interests.