Funding for this research was provided by:
European Research Council (ERC-2013-CoG 614739-A_HERO)
Received: 5 April 2019
Accepted: 23 December 2019
First Online: 6 January 2020
Ethics approval and consent to participate
: This study was approved by the the Zanzibar Medical Research and Ethical Committee (ZAMREC, reference number 0002/May/17) and the Ethics Committee of Northern and Central Switzerland (EKNZ, reference number 2017–00320). All participants provided written informed consent.
: Not applicable.
: The authors declare that they have no competing interests.