Background and Objectives: While the impact on mental health of 2019 coronavirus (COVID-19) has been extensively documented, little is known about its influence on subjective fears. Here, we investigate the COVID-19 impact and its related restrictions on fears of patients admitted to a psychiatric Emergency Department (ED) during and post-lockdown. Materials and Methods: A retrospective study on 1477 consultations at the psychiatric ED of the University Hospital of Geneva (HUG) was performed using a mixed-methods analysis. The first analysis section was qualitative, aiming to explore the type of fears, while the second section statistically compared fears (i) during lockdown (16 March 2020–10 May 2020) and (ii) post-lockdown (11 May 2020–5 July 2020). Fears were also explored among different patient-age sub-groups. Results: 334 patients expressed one/more fears. Both in lockdown and post-lockdown, fears mostly pertained to “containment measures” (isolation, loneliness). When compared lockdown vs. post-lockdown, fears about “work status” (deteriorating, losing work) prevailed in lockdown (p = 0.029) while “hopelessness” (powerless feeling, inability to find solutions) in post-lockdown (p = 0.001). “Self around COVID-19” (dying, getting sick) fear was relatively more frequent in youth (p = 0.039), while “hopelessness” in the elderly (p < 0.001). Conclusions: Collectively, these findings highlight that lockdown/post-lockdown periods generated temporally and demographically distinct COVID-19 related fears patterns, with special regard to youth and elderly, two particularly vulnerable populations when faced with sudden and unexpected dramatic events. For this reason, the particular ED “front-line service” status makes it a privileged observatory that can provide novel insights. From a mental health perspective, these latter can be translated into pragmatic, more personalized prevention strategies to reinforce specific resilience resources and mitigate the current and long-term pandemic’s impact.