Introduction The effort to prevent healthcare systems becoming overrun during the 2020 COVID-19 pandemic has come at the cost of delaying operations and with that bringing difficult risk analysis to help decide which operations should go ahead. With COVID-19 being a novel disease there is limited evidence for guidance on this issue. We have previously presented work highlighting the high risk of mortality associated with a perioperative cardiothoracic patient becoming COVID-19 positive and thus decided to implement a series of changes to departmental perioperative practice. This work presents these interventions and compares the infection and the mortality rate with those before the intervention was put in place. Method Two retrospective loops were performed. Pre intervention, 5/3/20 – 20/4/20, and post intervention, 21/4/20- 23/6/20. Inclusion criteria: patients who had received cardiothoracic surgery at University Hospital of Wales within 4 weeks of the positive COVID-19 PCR (1st loop n = 53, 2nd loop n = 40). Exclusion criteria included re-admissions from greater than 4 weeks (n = 2). Interventions included 14 day pre op isolation, a strict multifaceted screening regime, reverse barrier nursing and delaying operations if diagnostic uncertainty. Results 9/51 patients from the pre intervention loop and 2/40 from post intervention loop tested +ve for COVID-19. The pre intervention mortality was 5/9 and post intervention mortality was 0/2. Conclusion Our data suggest that simple changes to perioperative practice can decrease the transmission of COVID-19 during this period. Thus, allowing surgical services to run at a reduced risk