Were you officially diagnosed? I don't think they will give you an officially antibody test. Tests are in short supply.
No, my symptoms were never severe enough to warrant that. Also, the timing was off, I likely got it in Paris on 16-17 February (possibly at one of the two WHS, since there were big crowds at both sites ;-) ), but there was no "community spread" being reported anywhere in France at that time (but obviously it was really happening already.) I was almost over the disease by the time the number of cases around France exploded, and testing began in earnest.
The antibody test will be something completely different from the current test, which is in short supply. There is one company in the US planning on delivering it to the health services on 1 April, and fast-tracking approval for direct to consumer sales. It would be a fast at-home test similar to a home pregnancy test, but done with a drop of blood instead. This is presumably the same type of thing that Boris in the UK was talking about the other day, and I imagine the German system is working on it too. Eventually, the WHO, or a similar group, will want to do that test around the globe, perhaps numbering in the millions, because that will be the only way we will ever know exactly how many people were infected overall. So, I will eventually take it one way or another, but I don't know how long it will take before I can get one.
I think you will lose plenty of time at the border. They had a 2w mandatory quarantine and not sure how much they have relaxed this. Especailly seeing the most new cases are coming in from outside from China.
I think it's still 14 days, but, for such a hypothetical traveler, 14 days locked inside in Beijing is not really all that different from the lockdowns we are all experiencing elsewhere at the moment. ;-)
I'm going to get a t-shirt that says:
"I went to Paris, Banks of the Seine
, and all I brought back was Covid-19