Of course. (In a month, only the long-term-care residents and medical staff will have been vaccinated. I don't expect a turn until April or May. At that time, nevertheless, of course I'll keep my masks - I have several fanciful masks - because there are three or four levels of vaccine recipients behind me. )
Why would you?
Because, even if my body is producing antibodies, they're only 95% (max) effective, and they don't stop me passing the virus on the from an infected person to an uninfected one.
You won't catch covid and thus can't spread covid.
Wrong! You don't have to catch something to pass something. That's what carriers do. So do packages, fabric and impersonal clouds left behind someone who isn't even there anymore.
But the anti-maskers will look around and see many without masks (vaccinated folks) so why should they wear a mask if so many others are not wearing such?
They're already idiots. My example made no impression on them up to this point; it won't hereafter.
In a crowd, how does one tell the difference between the vaccinated and not?
You can't. So stay out of crowds.
Will the anti-maskers take advantage and pretend to be vaccinated (while not wearing a mask) when they aren't vaccinated yet?
Whatever happens in the real world has no effect on the idiots who have their alternate reality.
They are irrelevant, except insofar as it is wise to steer very far clear of them.
Do those vaccinated get a card that can't be replicated in Photoshop?
No.
What happens if you challenge a person not wearing a mask but claims to be vaccinated but can't produce a card or proof?
They'll probably spit on you, and might shoot you - so,
don't.
I suspect the answer will be mandatory masks.. always.. for everyone..
Voluntary for me.
until it's determined to safe for everyone, like next fall or so.
If we're very, very lucky. Probably much later; spring of 2022.
The anti-maskers will love that..lol.
Why do you care?