COVID-19 Case Definitions for Surveillance
Case and contact definitions are based on the current available information and are regularly revised as new information accumulates. Countries may need to adapt case definitions depending on their local epidemiological situation and other factors. All countries are encouraged to publish definitions used online and in regular situation reports, and to document periodic updates to definitions which may affect the interpretation of surveillance data.
The First Few X cases and contacts (FFX) investigation protocol for Coronavirus Disease 2019 (COVID-19). This is about identification 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 the identification of the initial laboratory-confirmed cases of COVID-19 in a country.