I am pretty sure there is a list of things that employers (in the US) can't discriminate on, and immunity to Coronavirus isn't one of them.
I think it will ultimately be in the hands of workers to decide whether or not they want to do the job. Maybe I'm immune to Coronavirus so I should work in a pharmacy... but I get paid 10x as much writing software, so I'm probably going to do that instead.
What if you’re immunocompromised with a hereditary illness? If there’s reasonable grounds it makes sense but reasonable and what employers will try and get away with are two different things.
My personal opinion is absolutely. But I'm 99% certain a vocal minority will spoil it for us.