Coronavirus disease (COVID-19) technical guidance by WHO Household transmission investigation protocol | Page 3

Summary: Several early investigation protocols are available for countries (https://www.who.int/emergencies/diseases/novel-coronavirus-2019/technical-guidance/early- investigations) 1. The First Few X cases and contacts (FFX) investigation protocol for coronavirus disease 2019 (COVID-19) (1). This is about dentification and tracing of cases and their close contacts in the general population, or restricted to close settings (like households, health-care settings, schools). FFX is the primary investigation protocol to be initiated upon identification of the initial laboratory-confirmed cases of COVID-19 in a country. For a more targeted approach on specific groups and more precise estimation of epidemiological parameters, three other investigation protocols are available: 2. Household transmission investigation protocol for coronavirus disease 2019 (COVID-19) 3. Protocol for assessment of potential risk factors for coronavirus disease 2019 (COVID-19) among health workers in a health-care setting (2). 4. Surface sampling of COVID-19 virus: a practical “how to” protocol for health-care and public health professionals (3). Please contact [email protected] for any questions. Main updates for version 2:       Technically edited version including consistency check and alignment with the three other early investigation protocols. Capture exposure also during the asymptomatic period of the confirmed case. Update of the Go.Data section, as now household questionnaires are available as templates in Go.Data for country use. Addition of an appendix describing the key features of Go.Data and several hosting options for Go.Data (Appendix C). Addition of an appendix on “Comparison between the features and complementarity of the main coronavirus disease 2019 (COVID-19) early investigation protocols”, now that the risk assessment for health workers has been published (Appendix B). Updated references, to align with the latest WHO guidance. -3-