Those people are _safe_. They can't catch the disease any more, which means they can't spread it (excepting on their clothes, I assume, which is probably reasonably low-risk).
That means that they're the best people to put on the front line. Get them on the tills at supermarkets, driving the food trucks, and opening the schools up (albeit only for children who have also got the antibodies).
Basically, we can start dividing the world into those who are safe and those who aren't - and the safe people can be a lot of use to those of us who are still waiting to catch it. Particularly the people who are at-risk.
I wonder how fast this could be scaled up.
Note: I am completely sure that this has drawbacks. If nothing else the tests will take ages to make available in volume. And it relies on much much more testing, (although we're going to end up doing a ton of testing for either the infection or the immunity, or both).
And it does rely on the immunity lasting a while. I'm hoping it will mostly last the two years that SARS did. If it lasts only a few months then we're in an awful lot of trouble.
Original post on Dreamwidth - there are comments there.