STAT asked a number of experts to map out scenarios of how we might come to coexist with this new threat. In a time of uncertainty, the scenarios they sketched were actually hopeful, even if the relief most envisage is not immediately around the corner.

“I don’t think we’ll be wearing masks in two to three years — for this virus,” said Vineet Menachery, a coronavirus researcher at the University of Texas Medical Branch in Galveston.

Menachery laid out four possible scenarios for how humans might interact with SARS-2 over time — in other words, what kind of immunity we might expect.

Some of the terms are of his own creation, so they may not be instantly recognizable to people who have studied immunology. They also cover a spectrum, and the lines between some of the scenarios can be blurry in spots. But they provide a useful discussion starter.

As Menachery sees it, the possibilities for the future when it comes to Covid-19 and human immunity break down as follows: sterilizing immunity, functional immunity, waning immunity, and lost immunity.