The new “traffic light” system ( that will replace lockdowns on Friday 3rd December) depends on "vaccine certificates” - requiring both employees and customers to show that they are fully vaccinated.
The traffic lights are:
Green: COVID-19 present, limited community transmission. Hospitalisations are at a manageable level.
Orange: Increasing COVID-19 community transmission and increasing pressure on health system.
Red: Increasing COVID-19 community transmission and increasing pressure on health system.
For larger events (anything over 100 people - concerts, festivals, large sports events etc) and hospitality businesses vaccination proof will be required at all times. Unvaccinated people will simply not be able to attend at all at any time.
For other businesses like retail and events like social gatherings etc the organiser/employer can choose whether or not to require vaccination.If they don’t require vaccination they will be limited to 100 people even at green and contactless trading (the old Level 3) at orange and red light levels.
If they do require vaccination they can trade normally at Green and Orange and will only be limited to 100 people under Red.
So there is obviously a significant advantage in requiring vaccination if Covid continues to spread in the community, remembering that 90%+ of adults will be vaccinated, and the government has said regions are likely to start at the "Orange" level at least, with some in "Red".