Received: 11 June 2018
Accepted: 22 May 2019
First Online: 24 June 2019
Ethics approval and consent to participate
: Ethical approval for the surveillance activities was obtained from the Kenya Medical Research Institute (KEMRI) Ethical Review Committee (SSC Protocol Number 1161). Institutional review was waived by US Centers for Disease Control and Prevention (CDC) because the study was considered to be a non-research public health activity. Informed written consent was obtained from all participants and from the guardians of minors.
: Not applicable
: The authors declare that they have no competing interests.