If we were going based off Israel's policy, it's antibodies, positive PCR and negative PCR.
Once we're making up new tests to use, I think my suggestion is more backed by medical science, which has never determined antibodies as a reliable predictor of future immunity. And in fact, we know that people who tested positive for antibodies months ago are getting it. We don't yet know of that means if they would have been tested for antibodies a week before they got sick whether they would have shown as positive or negative. There's just not enough data.
Israel's concern is if someone has the virus when they enter. Whether they had antibodies in April is wholly irrelevant. My comment was also predicated on the fact that if someone contracted the virus in the airport or on the plane, a test on arrival wouldn't catch it, as the minimum incubation period is believed to be 48 hours.
I don't see what bringing test results from months ago is supposed to be showing.
Here you are going on assumptions. No-one is talking about an antibody test from April (I don't think there were such tests back then) or even from June (when I got tested). Everything is predicated on a CURRENT test.
If someone doesn't have a positive PCR test, what would be a more reliable indicator of PUBLIC SAFETY, a rapid test upon arrival followed by a PCR test a couple of days later, both coming up negative, or a positive antibody test (and possibly a PCR test) shortly prior to arrival, followed by a negative PCR test upon arrival? Please tell us based on your own logic, and/or based on any medical research, documentation, or report.