Let’s be frank. 

If a vaccine does not prevent infection or transmission, there is no scientific basis for a vaccine passport. 

I know there are plenty of people who want a reward for nineteen months of good behaviour, but the vaccine is your reward. That is the point of vaccination. We give lolly-pops to children, not emotionally insecure adults. 

Even if the vaccine prevented transmission, governments have no right to play with domestic vaccine passports.