Here is my concern with requiring vaccinations: what happens when we get down to people under 30, say? What about under 20? Do we still require the vaccine? What's the cutoff?
The reason I ask is that at present we don't really know if it's going to turn out that the narrow acquired immunity offered by the mRNA vaccines will ultimately prove to be as good as the innate immune response in young people. But if you give them that acquired immunity, you run the risk of their bodies preferentially deploying that specific immune response against variants...even if it stops working against those variants.
My understanding is that the mRNA vaccines have been coded to attack the spike protein that we've all heard about and that works very well, at the moment...but it doesn't have to. And by vaccinating billions of people during a pandemic, you essentially create a giant system to apply selective pressure to the virus, as well as staggering numbers of copies floating around out there to mutate. If you wanted to drive a type of mutation that helped the virus avoid the acquired immune response conferred by the vaccine, this is pretty much the perfect way to do it.
Those mutations may not happen to a degree that generates dire consequences but that would be luck. The evolution of the new strains we're seeing is exactly this process taking place and so far it's hard to say what the results will be but scientifically, from a viral evolution perspective, there's no reason to think that the virus CAN'T evolve such that the spike protein that the mRNA vaccines recognize, is still present, but no longer a vulnerability.
If that happens, there's a huge problem: if you've primed the immune systems of young people to respond with that particular acquired immunity, their innate immunity which is a general system that attacks anything it doesn't recognize, won't engage. Only the now-useless acquired immune response will. The thing that currently makes young people safe, would be gone.
That's a whole lot of "if" and none of that may ultimately take place and there may turn out to be reasons it's not a likely outcome, but scientifically, that's valid. It's a real possibility.
So my concern about vaccine passports is: what if they drive young people to get a form of immunity that ultimately turns out to be worse than the one they currently have? To me that's a pretty serious problem and it's another factor in why, although I fully intend to get the AZ vaccine when I can, I would be a lot more hesitant to vaccinate my kid until after the pandemic phase is over and the whole world isn't a giant viral lab generating new strains. India alone must be germ warfare central right now in terms of sheer numbers of mutations occurring...it's totally possible that narrowly targeted vaccination programs in that environment are going to drive something even worse. It's real-time gain-of-function research being carried out in a totally uncontrolled way.
Gain of function research, incidentally, being exactly the research done at the Wuhan lab on bat coronaviruses that used to be really terrible at jumping to humans, and even worse at transmitting from human to human. So there is a genuine risk here.
I'm not at all anti-vaccine, but this situation is complicated and the problem with vaccine passports is that is starts with the conclusion: you should definitely be vaccinated, now, with the vaccines available. We don't actually know if that's going to turn out to be true and I have serious concerns about restricting the freedoms of people who could conceivably turn out to have been right not to get vaccinated under these specific circumstances. They could be wrong, but I have a real problem with forcing people to undergo a procedure that modifies their immune system in the midst of a global outbreak on this scale, which is something that we've literally never done before and don't know what the consequences are.