This open question has huge bearing on how soon we can reopen the economy, what the course of this disease could be beyond the first wave, how successful an eventual vaccine might be, and how we should treat those who have recovered.

The short answer: it’s too soon to know fully. But positive signs are emerging that at least a limited immunity is more likely than not.

The Boston Globe has an outline of two of the first peer-reviewed papers reporting on immunity to Covid-19 in primates. They were published last week in Science. The upshot is that immunity does indeed develop, at least in rhesus macaque monkeys, both after recovering from the disease and after application of an experimental vaccine. There is of course no guarantee that these results will carry over to humans, but these monkeys do share 93% of humans’ DNA.

And a second press account from last week provides some clarity on early reports of people testing positive again weeks after recovering from Covid-19. It seems that the most optimistic possible explanation for those results is the correct one: the tests were picking up fragments of SARS-CoV-2 RNA, not contagious live virus. Re-infection wasn’t happening.

Finally, see this New Yorker report for a wide-ranging survey over what is known about immunity as it bears on questions of any kind of officially sanctioned “immunity passport.” Be sure to read the final two paragraphs on the promise of epigenetic testing — which if it can be made to work could help to avoid future lockdowns whether or not immunity passports come about.