With the Covid-19, the world experienced an unprecedented crisis in 2020: the human impact, the restriction of freedoms, starting with the restriction of freedom of movement, economic shocks and their social consequences, are among the most striking facts. It should be added that rarely have States measured their degree of interdependence and therefore their weakness to this extent. Societies have thus been confronted with their vulnerability: our understanding of security and peace should therefore be profoundly revised. The first part introduces the analysis of the health crisis in the light of past crises and the possibilities offered by early warning; then it is international relations and the loss-gain game observed at the level of States that are investigated, the crisis being perceived here as a structure of opportunity. Finally, the third part sheds new light on several domains: the religious field, the academic field, the military world. The notion of risk is central.