Study design and sample collection
We adopted a cross-sectional active sentinel surveillance study design. The study population included any person aged six months and above. At each sentinel site, the first five patients meeting the case definition of a suspected SARS-CoV-2 case were eligible for recruitment per day. Each participant signed a written informed consent form in either English, Kiswahili, or the local dialect; for minors, parents or guardians supplied the written consent. Children aged between 13 and 17 were asked to assent to participate in the study after consent had been sought from the caregiver. Socioepidemiological and clinicopathological patient data from each case was recorded using a standardized questionnaire including a unique identifier, demographics, symptoms, and pre-existing conditions onto ODK collect Version 4.4.