The future of America’s Covid-19 epidemic can now be distilled into this: long-term confidence and hope, but short-term uncertainty and, perhaps, even despair.

Vaccines are rolling out quickly, setting up the country to crush the outbreaks that have warped our lives for the past year.

But in the short term, perhaps the next month, the US faces a few potential paths. The worst scenario: A fourth surge of the coronavirus outpaces vaccinations and kills thousands more people even as the country nears the finish line with Covid-19. The best possibility: The accelerating vaccine rollout and continued vigilance keep the virus at its current level or, hopefully, results in fewer infections — letting the US cross the finish line safely and with more lives saved. Then there’s a middle path: Cases rise, but vaccines shield the country from more hospitalizations and deaths.

The path the US takes, though, will be decided by one of the most unpredictable things of all: human behavior.

The public could loosen up on Covid-19 precautions too quickly, discarding masks and failing to social distance before enough people are vaccinated. As has already been done in some areas, policymakers could push the country in this direction by ending restrictions before the vaccine rollout is truly at critical mass. Either of those things, or a combination of both, could lead to a fourth surge.

But if Americans hold out just a bit longer, and vaccination rates continue to pick up, the US could reach the end of the current large outbreaks — as cases dwindle down close to zero — before that happens.

The good news is, an end seems to be in sight. At current vaccination rates, the country could inoculate its entire adult population by July, leaving us ample time over the summer to start getting our lives back to normal and, hopefully, celebrate with others. One country that has vaccinated the bulk of its population, Israel, has shown this is possible, reopening its economy and crushing the Covid-19 curve at the same time.

“Yes, there are some near-term concerns,” Jen Kates, director of global health and HIV policy at the Kaiser Family Foundation, told me. “But so far we’re — cautiously — on the other side of it. … If we push ahead and really accelerate vaccination, by the summer we’ll be in a much, much better place.”

The question now is what lies between here and there.