I can present to you a very good reason not to use immunity status. Every idiot and their brother was discussing how they had already had it when statistically this was absolutely impossible. Everyone who had the sniffles from late 2019! to current is absolutely sure they have had it because it would be more convenient to be immune than not.

It would be impossible to give antibody tests to 60M antivaxxers in any reasonable time frame. Instead of asking people to wait in line a year for a test that has very little medical use the politically expedient thing would be to ask for the equivalent of a doctors note saying they pinky swear their patient had covid. Some states/some doctors would fire up the presses and within a month 95% of the antivaxxers there would have a certificate regardless of actual status.

Since vaccination is actually in everyone's interests even if they have already had covid this would lead to less people being vaccinated and it would be against even the anti vaxxers interests and furthermore locations that only allow vaccinated or tested people would now be equally full of infectious people as vulnerable people with a newly false sense of security.

> Some states/some doctors would fire up the presses and within a month 95% of the antivaxxers there would have a certificate regardless of actual status.

Then test them and fire the doctors who deciced to lie.

Other countries, notably Israel do allow it. Their scientific establishment is apparently a lot smarter than the one in the U.S. Or maybe less corrupt? We can only guess at the motivation behind apparent incompetence of these agencies, often referred to as "conspiracy theorizing".

This seems like a reasonable approach and it’s been talked about. Is there anything stopping individual states from issuing such certification?

> This begs the question, why not simply use immunity status instead of vaccination status? If someone has the right antibodies to fight COVID, does it matter how these were obtained?

Because humans love any opportunity to discriminate against another group of people. Despite this discrimination making zero sense, since clearly us vaccinated people are still spreading COVID at very high rates.

1. To err on safe side - better have 2 immunities than 1 (esp when it's self reported)

2. Unity - we're in this together and I'm sorry if you live in a place where communities are disconnected

We're in this together sounds a lot more like "You're in this with me."