This research intends to study the response of different organizations to the Covid-19 pandemic, comparing the period from March to May 2020 with the period beginning in October 2020. It will focus on three sets of organizations: 1) Government and central administrations, 2) regional and local institutions, 3) the (socio-)health sector. The interviews conducted will be organized around three thematic entries that will help us to better understand the relationships between the different actors and organizations: 1) protection and prevention measures (masks, lock-down, curfew, isolation and physical distancing) ; 2) the organization of tests and screening (availability and choice of tests, contact cases, applications); 3) the management of patients and populations at risk (in hospital, at home, respiratory equipment, treatments, transportation). This research aims to uncover and analyse the capacities of these organisations to transform themselves or not in a period of uncertainty, by favoring an approach centered on collective action (to analyse the forms of cooperation or conflict that arise during crisis management) and a cognitive approach (which looks at the way in which actors make sense of the crisis and legitimize their actions). By comparing two periods, we will seek to see whether the capacities for cooperation differ according to whether the situation is marked by a high degree of uncertainty, urgency and extraordinary functioning; or, on the contrary, a better knowledge of the risks, less time pressure and a return to ordinary functioning. The goal will be to produce, in addition to fundamental knowledge about organizations in crisis situations, an analysis shared with the actors involved in the management of the crisis in these different organizations, with a view to collective learning.