https://blogs.scientificamerican.com/observations/beware-of-antibody-based-covid-19-immunity-passports/

COVID-19 has rendered conventional passports pointless for the foreseeable future. But many countries are exploring the idea of a new type of “immunity passport” to permit people with antibodies against the COVID-19 virus to escape lockdowns. The alluring premise is that these individuals are immune and thus could be permitted to work and travel, a step towards returning to a pre-pandemic society. This ostensibly scientific approach is actually a colossally unsound, and possibly dangerous, idea.

If, as touted, an antibody test will determine the fate of our $21 trillion economy, and also protect us from a deadly respiratory virus, then we should demand a high-quality test. Yet, dozens of tests with unknown accuracy have flooded the United States market, thanks to a move by the Food and Drug Administration that loosened restrictions in order to increase access to testing. It is not clear when, or if, we will know how well these antibody tests work, though the FDA announced in mid-April that researchers at the National Institutes of Health would begin evaluating the quality of these tests.