The COVID-19 epidemic was an opportunity to put private consultancies and their participation in the public management of the health crisis in many countries in the media and political spotlight. Nevertheless, this phenomenon is not new and many social science studies have shown the increase, and even the normalisation, of the interventions of these firms with administrations for more than 30 years (Saint-Martin 1999; Henry 2012; Bezes 2012; Belorgey and Pierru 2017; Kipping 2021). However, studies on the role of these firms in the context of public management of epidemics remain rare. This research project aims to understand the nature of this intervention from a socio-historical perspective. The aim is to study the place occupied by these firms in public epidemic control mechanisms since the 2000s, the expertise mobilised and their effects on public action and on the functioning of administrations in the context of epidemics. The research is based on two complementary methods: a review of the scientific literature on the subject and a French case study. The first, a scoping review, allows us to take stock of knowledge and theoretical and methodological approaches to this subject. It also allows for the preparation and problematisation of the second part of the research: a qualitative survey by means of semi-directive interviews with agents of French central or decentralised administrations in charge of these issues and consultants from consultancy firms.