But from a scientific point of view, a qualitative rapid...

But from a scientific point of view, a qualitative rapid antibody test not actually checking for the presence or absence of antibodies. It’s checking for an antibody concentration above or below the threshold that the RDT is designed to check for. Behind the scenes doctors and scientists in a few countries are also doing actual formal quantitative antibody studies in smaller groups of patients (still hundreds or thousands) over time to observe how high antibody levels get after vaccination or infection and then how quickly or slowly the levels drop. We can assume for now that the rapid antibody test threshold is in line with what the quantitative studies suggest is required, but we don’t actually know this and it could change as new evidence emerges.