Yes, but not one that is ethical. You do a challenge experiment to those with antibodies and see if they get infected. The next best alternative is monitoring

Yes, but not one that is ethical. You do a challenge experiment to those with antibodies and see if they get infected. The next best alternative is monitoring a large number of people with antibodies (and a control group) for new infections. This is slow and expensive, but if you have enough people then it will work.