Intensive care unit (ICU) staff have faced unprecedented levels of stress, in the context of profound upheaval of their working environment due to the COVID-19 pandemic. We explored the perceptions of frontline ICU staff about the first wave of the COVID-19 pandemic, and how this experience impacted their personal and professional lives. In a qualitative study as part of the PsyCOVID-ICU project, we conducted semi-structured interviews with a random sample of nurses and nurses' aides from 5 centres participating in the main PsyCOVID study. Interviews were recorded and fully transcribed, and analysed by thematic analysis. A total of 18 interviews were performed from 13 August to 6 October 2020; 13 were nurses, and 5 were nurses' aides. Thematic analysis revealed three major themes, namely: (1) Managing the home life; (2) Conditions in the workplace; and (3) the meaning of their profession. In this qualitative study investigating the experiences and perceptions of healthcare workers caring for critically ill patients during the first COVID-19 wave in France, the participants reported that the crisis had profound repercussions on both their personal and professional lives. The main factors affecting the participants were a fear of contamination, and the re-organisation of working conditions, against a background of a media "infodemic".