From a public-health standard, the pandemic will not end for another 18 months. The only complete resolution—a vaccine—could be at least that far away. The development of a successful vaccine is both difficult and not sufficient. It must also be manufactured, distributed, and administered to a nation’s citizens. Until that happens, as recent reports from the U.S. government and from scientists at London’s Imperial College point out, we will be vulnerable to subsequent waves of the new coronavirus even if the current wave happens to ebb.

None of which means that people now hunkered down at home will keep doing so through late 2021. The economic consequences of an indefinite lockdown are unsustainable. And at a certain point, the emotional tensions that staying home imposes upon families, as spouses grate upon each other and children get bored and fall behind on their schoolwork, become a danger to domestic harmony, and maybe even to everyone’s sanity.

At the moment, we are just playing for time. Whether social distancing is working will be clearer in a month than it is now, but even then we will not know to a moral certainty when adults can safely go back to the office and children can go back to school. Which is partly why employers, university officials, and others have given such widely varying time frames for how long they are shutting things down—two weeks, until the end of April, until the end of the academic year, until sometime later.

Two weeks, for what it’s worth, is just a way of breaking the bad news easily. If anything, we are likely to see more draconian distancing measures if the data start to show success. The goal of social distancing, as everyone now knows, is to “flatten the curve”—to keep the number of COVID-19 cases from spiking faster than the medical system can mobilize to handle them. But a flatter curve is longer; a failure of social distancing would mean the peak comes sooner—at a horrifying cost of lives—but also that Americans are back outside sooner.

If entirely suppressing the coronavirus is a public-health ideal, crisis management is the homeland-security standard. The goal is to minimize risk, maximize defenses, and maintain social cohesion at the same time. In a society that must start moving again at some point, emergency-management planners looking at the metrics may seem heartless.

Read: Why the coronavirus has been so successful

In the military, commanders must make calculations about acceptable losses; the benefits of a mission have to be weighed against the certainty that some soldiers will be lost. We don’t have such language in the homeland-security world, but trade-offs are still inevitable. The wrenching decision to open up again—to accept more exposures to the coronavirus as the price of an earlier economic revival—is simply a judgment call. It is too late to prevent tragedy entirely; our goal is to manage it within the limits of scientific progress and public tolerance.