Covid vaccine and test passes to be introduced in Wales

[Welshcake.]

This is what I don't get. If the vaccines don't stop people getting covid and transmitting covid but they are effective at stopping serious illness what is the need for vaccine passports? In other words those who are vaccinated are protected from serious illness so what difference does it make to them lf they come into contact with someone who is vaccinated or not vaccinated?

It's quite simple a vaccinated person is less likely to catch covid (efficacy 68% AZ, 82% Pfizer).

This makes a room (or stadium in this case) full of vaccinated people a safer space than a room of unvaccinated people. All people are less likely to have covid and less likely to catch it.