I don’t find anything about developing immunity from exposure, but the UK is going to test the idea for us.
The government’s Chief Scientific Adviser says they won’t be implementing a drastic shutdown like closing schools and banning large public events.
Financial Times – March 13, 2020 – ’ “Communities will become immune to it and that’s going to be an important part of controlling this longer term,” he said. “About 60 per cent is the sort of figure you need to get herd immunity.”
“In another interview with the BBC Sir Patrick said: “If you suppress something very, very hard, when you release those measures it bounces back and it bounces back at the wrong time.” ’
UPDATE: I see that Financial Times link hits a paywall if you go direct. It seems you can read the story if you google it and click the link.