This guide covers the steps for detecting and managing transmission chains and clusters of COVID-19 infections, particularly in communities. It does not include management measures for isolated cases occurring within a community. Its objective is to provide a common framework for professionals working at Level 3 of the contact-tracing system, for: identifying transmission chains or clusters; investigating them; proposing specific control measures (such as facility closures), depending on the types of situations encountered; and defining the resources required for each of these steps. This framework is intended to be adapted to the regional organizations established and shared with the ARS departmental delegations and health insurance platforms. It is supplemented by action sheets tailored to the locations or circumstances where clusters occur. These may evolve based on accumulated experience and can be usefully adapted to the context of each region. Similarly, depending on how the cluster evolves (spread outside the community, for example), investigations must be expanded beyond the community to identify and break all transmission chains.