© 2020 The Authors. The Clinical Teacher published by Association for the Study of Medical Education and John Wiley & Sons Ltd Background: Simulation training is an effective tool for improving confidence in healthcare workers. During the recent COVID-19 pandemic, large numbers of staff required re-training to manage unfamiliar situations. We present a set of medical student-led clinical simulation sessions and evaluate their effects on (i) confidence among redeployed healthcare workers managing COVID-19 patients and (ii) medical students’ confidence as educators. Methods: Half-day simulation training sessions consisting of three COVID-related clinical scenarios were devised by senior medical students and delivered to a group of approximately 150 healthcare workers over six repeated sessions prior to redeployment to COVID-19 wards. We distributed an anonymous pre- and post-simulation questionnaire to 36 participants in the final group exploring their experiences. The confidence scores were analysed using the Wilcoxon signed-rank test. Following the delivery of teaching, medical students completed a questionnaire assessing their personal experiences of designing and delivering the exercises. Results: Data are available for 35/36 participants approached. Respondents reported being significantly more confident after the training in all aspects of managing COVID-19 patients, including triage, complex discharge, recognising deterioration, initiating basic life support, managing symptoms and advising on visiting policies (p < 0.001); 97% of respondents rated the training as useful. Thematic analysis of medical students’ responses demonstrated mutual benefit. Discussion: This study demonstrates the strengths of simulation training in helping to build staff confidence in a rapidly evolving situation and highlights the value of medical students in supporting a hospital’s response to an outbreak. We recommend further studies of student-led simulation exercises, including longer-term follow-up.