Background: Intensive care unit (ICU) healthcare workers (HCWs) are at the forefront of the coronavirus disease 2019 pandemic. To overcome the lack of human resources during this crisis, some ICUs had to mobilise staff from a reinforcement pool, with no or outdated ICU experience. This study aimed to investigate and to compare the psychological impact of the pandemic on regular ICU staff members and reinforcement workers. Material and methods: Self-assessment questionnaires were completed by HCWs who worked from March 1 to April 30, 2020, in our 16-bed neurological ICU at La Pitié-Salpêtrière Hospital in Paris, France, which was converted to a COVID ICU. The Hospital Anxiety and Depression Scale, the Post-traumatic Stress Disorder Checklist for DSM-5, McGill Quality of Life Questionnaire-Revised, and 10-item Connor-Davidson Resilience Scale were used to assess anxiety, depression and post-traumatic stress disorder, quality of life, and resilience, respectively. Results: Sixty-nine ICU HCWs completed the survey (37 from the team of regular staff members, i.e., from the public health service, and 32 from a reinforcement pool, either from non-ICU public health service or from private healthcare interim employment agencies). Prevalence of anxiety, depression, and post-traumatic stress disorder symptoms was high, at 19%, 9%, and 16%, respectively, with limited impairment in quality of life or resilience scores. Depression symptoms were observed more in regular staff members than in welcomed reinforcement workers, at 16% and 0%, respectively. Conclusions: These results revealed that during the pandemic, HCWs from the team of regular staff members were at greater risk of developing psychological disorder compared with reinforcement workers, with higher levels of depressive symptoms.