Well, yes, antibodies! But it looks like this virus, like its relatives, mutates enough that infection with one strain doesn't mean you can't get it again. So this may be a situation where many of us (or at least those working or living with vulnerable populations) will have to get an annual shot.
https://www.ajmc.com/view/first-case-of-covid-19-reinfection-detected-in-the-us
If you're a healthcare worker, work with the elderly, or work in a school in most places, you have to certify that you're not passing on TB, and that you have relevant immunizations.
The other thing that frets at me is that yes, the fatality rates for Covid-19 can be low, but that assumes that the resources are there. When the medical facilities got overwhelmed in northern Italy this spring, they were logging fatality rates (for confirmed cases) at a brisk 18.3%. Now, there must have been some asymptomatic cases, but that's the model that the rural Midwest is looking at for January as regional hospitals and critical care facilities go down under the surge.
(Source: https://www.thelancet.com/journals/lanpub/article/PIIS2468-2667(20)30099-2/fulltext )
And demographically, that's an older population with more health complications than the urbanized coasts. I don't want to write off Kansas or any significant portion thereof.