As vaccination coverage against SARS-CoV-2 increases amidst the emergence and spread of more infectious and potentially more deadly viral variants, decisions on timing and extent of relaxing effective, but unsustainable, non-pharmaceutical interventions (NPIs) need to be made . An individual-based transmission model of SARS-CoV-2 dynamics, OpenCOVID, was developed to compare the impact of various vaccination and NPI strategies on the COVID-19 epidemic in Switzerland . We estimate that any relaxation of NPIs in March 2021 will lead to increasing cases, hospitalisations, and deaths resulting in a``third wave"in spring and into summer 2021 . However, we find a cautious phased relaxation can substantially reduce population-level morbidity and mortality . We find that faster vaccination campaign can offset the size of such a wave, allowing more flexibility for NPI to be relaxed sooner . Our sensitivity analysis revealed that model results are particularly sensitive to the infectiousness of variant B.1.1.7.