As countries move ahead despite limited knowledge, whole societies are becoming unwitting test subjects of what works — and what they're willing to give up.
The world is entering a period of high-stakes experimentation, with cities and countries serving as open-air laboratories for how to most safely and effectively reopen amid the coronavirus.
Unable to wait indefinitely for science to answer every riddle about what makes infections spike in some circumstances and not others, governments are pushing ahead with policies built on a growing but imperfect understanding of the virus.
And with little consensus on how best to balance public health against social and economic needs, societies are feeling their way through trade-offs that would be gut-wrenching even with better information on any given policy's likely cost in lives and livelihoods.
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"We're in the middle of a global trial-and-error period to try to find the best solution in a very difficult situation," said Tom Inglesbury, who directs the Center for Health Security at Johns Hopkins University.
The first wave of reopenings, predominantly in Asia and Europe, are providing a preview of what could become a continual process of experimentation and recalibration.
Each policy, like distancing students at Danish schools or temperature checks at Hong Kong restaurants, however based in scientific knowledge and calculated cost-benefit, is also a trial of what works, what's worthwhile and what people will accept.
Though experience bought in lives will convert some unknowns to knowns, many questions may remain unanswered for the duration of what is expected to be a one-to-two-year crisis.
That includes what may be the hardest but most urgent question of all: What is the value of a life saved?
Countries have little choice but to guess at stomach-turning ethical calculations. How many lives should be risked to save a thousand people from unemployment? To stop a generation of kids from falling behind in school? To salvage a sense of normalcy?
While Inglesbury stressed that "there are a lot of principles that are based on public health and common sense" to guide us, he also said, "There's no road map for this."
Navigating the unknowns
Many countries' policies are shaped, in part, by how they navigate the gaps in knowledge about the virus.
For example: Does being outdoors drastically limit transmission?
Lithuania, on the belief that it does, is closing streets in the capital to allow restaurants and bars to open outdoor-only services.
Others are testing this hypothesis more tepidly. Bangkok is reopening parks but forbidding most activities that involve multiple people. Sydney is reopening beaches for swimming and surfing but not sunbathing or socialising.
Another mystery: How easily, and widely, do children transmit the virus?
Some countries are reopening schools, taking a calculated risk on indications that children might be relatively safe, while imposing restrictions in case they aren't.
Denmark is opening schools to younger children, who are tentatively thought to be less at risk, but hedging with restrictions on class size.
Germany, meanwhile, is inviting back older children who, the thinking goes, might pose a higher risk of transmission but will better comply with rules on masks and distancing.
There is another set of unknowns: those pertaining to people's behavior.
South Korea's government is gambling on citizens voluntarily observing a litany of guidelines on everyday interactions, like bowing instead of hugging at funerals.
In other areas, it is less trusting, using fines and digital monitoring to enforce mandatory quarantines for those thought to have even come into contact with an infected person.
California will allow some businesses to offer curbside pickup, in the hopes that enough workers and consumers will embrace this, and safely enough to halt the economy's free fall without infections resurging.
Georgia, meanwhile, lifted restrictions on businesses only to find that customers were largely unwilling to come back.
Any reopening measure aims "to balance at least three different things," said Ezekiel J. Emanuel, chairman of the Department of Medical Ethics and Health Policy at the University of Pennsylvania.
These are: Keeping infections low, to prevent health services from getting overwhelmed; keeping deaths low, which entails deterring higher-risk infections; and controlling economic and social burdens.
But even if we expect a given policy to improve one metric and worsen another, gaps in knowledge about the coronavirus mean we don't know by how much.
"Figuring out the right balance is obviously the chief problem here," Emanuel said. "It's really hard."
German officials who partially reopened factories, for example, have little way of anticipating either how many people will get sick or how many jobs will be saved as a result.
The only way to know for sure whether a policy's upsides are worth its costs is, in many cases, to try it and watch what happens.
Each step toward reopening, then, is also a set of experiments with whole societies serving as guinea pigs — or, if you prefer, explorers stepping boldly into the unknown. Either way, few expect the process to be clean.
"I think it's unlikely we'll get the balance all correct at the start, since it's the first time we're doing any of this," Inglesbury said.
Sure enough, Germany's infection numbers ticked back up, though modestly enough that the country continues its slow reopening.
India, on the other hand, saw a sharper increase after some restrictions were lifted — raising the possibility of a return to lockdown, as some Chinese cities have already done.
Even failed experiments might offer hard-won lessons, in theory allowing each reopening to be safer than the last.
"Is there a resurgence of cases based on particular patterns of easing social distancing?" Inglesbury asked. "Do we discover that there are cases occurring in mass transit? Are the things that Hong Kong is doing with restaurants working?"
But there is a wrinkle: Cities and countries are tending to change several things at once, and that makes it hard to isolate specific lessons. A policy might appear to fail in some circumstances and succeed in others, slowing the world's ability to learn.
Even if the world could quantify with certainty how a particular policy affects both the virus and social welfare, there is no formula for how to balance the two.
That has forced world leaders to confront a question that ethicists have wrestled with for years: How much should society be willing to sacrifice to save a life?
Put another way, how many people should lose their jobs to save one life, knowing that extended unemployment is associated with reduced life expectancy? How many people should be allowed to die if it lets a community keep the local factory running?
"One of the things that's new here is the trade-off between people's long-term futures," said Emanuel, the medical ethicist.
With no easy formulas or answers, he said, "Someone's got to make those trade-offs. I don't know what else to do."
For President Donald Trump, more than any other leader so far, the upsides of reopening exceed even the most extreme risk — he is also among the only leaders to push for reopening as cases continue rising in many parts of the country. That, experts warn, could invite more economic damage than relief.
Other courses of action demand weighing human life against civil liberties, social inequality, even cultural value.
South Korea is taking steps toward restarting its baseball league, which is both a business and a source of enjoyment for millions. Hong Kong is allowing some access to libraries.
And Americans are already debating whether there is a point at which enforcement of social distancing — through monitoring, fines or outright coercion — carries unacceptable costs to individual liberty.
What begin as economic or public health questions quickly become, with no other way to answer them, matters of philosophy and values.
How aggressive should schools be in reopening? New outbreaks might imperil adults who are older or have preexisting conditions. But a year of lost school can set back a child for life.
Is the value of partially reopening a cultural site like Broadway measured in economic terms alone, or also in the happiness it brings to theatregoers, and its contribution to culture? Is that enough to put lives at risk?
Concessions in freedom and privacy — already being made in individualistic South Korea — could endure after the pandemic is over. The choices that are made could add up to societies reconfigured around the values that informed them.
As the consequences of those choices mount, the costs of fighting the pandemic will become clearer every week.
"It's going to be a very difficult balancing act," Inglesbury said.
Written by: Max Fisher
Photographs by: Alessandro Grassani, Lam Yik Fei, Emile Ducke and Adam Dean
© 2020 THE NEW YORK TIMES