Michael T. Osterholm is regents professor and director of the Center for Infectious Disease Research and Policy at the University of Minnesota. Mark Olshaker is a writer and documentary filmmaker. They are the authors of “Deadliest Enemy: Our War Against Killer Germs.”

Covid-19 will go away eventually in one of two ways. Either we will develop a vaccine to prevent it, or the virus will burn itself out as the spread of infection comes to confer a form of herd immunity on the population. Neither of those possibilities will occur quickly.

It is time to face reality. We urgently need a unified national strategy, one informed by the best science about stopping diseases like covid-19 and from virus control efforts in China, Singapore and Hong Kong, as well as realistic projections of the human and economic toll of any option we pursue. Our way of life cannot survive an indefinite series of short-term action plans.

We have to ask what we hope to accomplish with limited self-quarantines and shelter-in-place directives. Clearly, as one objective, we seek to “flatten the curve” in an effort to keep our already overburdened health-care system from being overrun. The ability of our hospitals to continue providing care to a flood of covid-19 patients, while still treating the other patients they normally have, all the while protecting health-care professionals, will be a major factor in reducing bad outcomes for victims of the coronavirus and other illnesses as well.

But how do we actually accomplish this? What happens after a several-week moratorium on normal activity? Does the president, governor or mayor declare another? While California Gov. Gavin Newsom (D) has made a courageous move by locking down his state, how long can 40 million California residents be kept at home? And will it be long enough to make a significant difference?

China and Italy have imposed near-draconian lockdowns in an effort to halt the spread of covid-19. But how and when will these two “test” nations return to normal life? And when they do, will there be a major second wave of cases? If that happens, should they simply “rinse and repeat”?

As a country, with momentum building for a possible national shutdown directive, we are on the verge of ringing a giant bell that we don’t know how to un-ring.

Yet we don’t, for example, have good data on the real impact of closing public and private K-12 schools on the spread of covid-19. Hong Kong and Singapore, advanced city-states that experienced the outbreak early, both attempted to respond quickly and efficiently. Hong Kong closed schools; Singapore did not, and there was hardly any difference in the rate of transmission. The second-order effect of shutting schools is that hardest hit will be those least able to afford to miss work to care for homebound children. And what of our health professionals with children? Add to that firefighters, police officers, utility workers, delivery drivers and other essential personnel, and the magnitude of the problem is clear.

The Imperial College of London has produced a sobering study on possible covid-19 strategies. Three scenarios compare the outcomes of flattening the curve (mitigation), suppression (long-term quarantine) and letting the virus take its natural course (doing nothing), modeling the levels of disease and death for each course. The stark takeaway: Significantly reducing the number of serious illnesses and deaths would require a near-total lockdown until an effective vaccine is available, probably at least 18 months from now.

Consider the effect of shutting down offices, schools, transportation systems, restaurants, hotels, stores, theaters, concert halls, sporting events and other venues indefinitely and leaving all of their workers unemployed and on the public dole. The likely result would be not just a depression but a complete economic breakdown, with countless permanently lost jobs, long before a vaccine is ready or natural immunity takes hold. We can’t have everyone stay home and still produce and distribute the basics needed to sustain life and fight the disease.

We are in uncharted territory. But the best alternative will probably entail letting those at low risk for serious disease continue to work, keep business and manufacturing operating, and “run” society, while at the same time advising higher-risk individuals to protect themselves through physical distancing and ramping up our health-care capacity as aggressively as possible. With this battle plan, we could gradually build up immunity without destroying the financial structure on which our lives are based.

Very soon, we may have to acknowledge that attempting to stretch out cases in the hopes of keeping the curve reasonably flat is unworkable. Then, as we wait for either our scientific or natural redeemer to come, we can start trying to put things as back to normal as we can — doing our best to protect those at high risk, but acknowledging that people will get sick, some will die, and our health-care system is going to be overrun to a great extent no matter what we do.

There is no black-or-white option here. We will have to figure out what shade of gray we can accept and apply. We will get through this, but hard and painful choices are inescapable.

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