Pressed by swiftly falling revenue amid the coronavirus pandemic, corporate America has begun looking for ways to enable U.S. workers to return to factory floors, warehouses and offices.

President Trump has created an “opening our country" task force with the goal of restarting the economy by May 1. And while many question the timing, everyone from small manufacturers to major brands such as Whirlpool and retailing giant Amazon are taking steps to get their workers back on the job.

Mostly that involves testing on a scale that is, for now, out of reach.

“Rapid testing … is going to be the bridge to the new economy and getting to work and restarting,” Gov. Andrew M. Cuomo (D-NY) said during a recent news briefing “We’re not going to go from red to green. We’re going to go from red to yellow. Yellow is, let the people who can go back to work start going back to work. Well, how do you know who can go back to work? Test them. You have rapid testing capacity. We have to bring it to scale.”

Two types of tests are in demand. One is a diagnostic test to determine whether a person has covid-19, the disease caused by the novel coronavirus. Another, still being developed, is designed to tell if one has developed immunity to the virus. Both will be needed to ease the current U.S. lockdown.

But even if the number of tests expands significantly, the nature of the virus and the design of the American workplace make coming up with a back-to-work plan difficult.

The trend toward open workspaces means employees breathe the same air. Crowded elevators and public transportation pose perils. In addition, employers must respect health privacy laws but they need to share enough of that data if a worker has tested positive for the virus and those in contact with that person need to be quarantined. Meanwhile, people who test positive for antibodies to the coronavirus could still spread it. And most covid-19 testing still has high levels of false negatives.

“While there is lots of pressure to get people back to work, it is far from clear if work will be safe,” said Bob Kocher, a physician and partner at the venture capital firm Venrock who serves as a member of California’s testing task force.

Bob Terbrueggen, chief executive of Los Angeles-based DxTerity, thinks he has just the thing. The small diagnostics company has a plan where businesses would screen workers every week or two. DxTerity would provide kits to test for infection — employees would swab nasal passages and spit into a bar-coded tube, send the samples back to the company, and get results the next day. “You can think of the nucleic acid detection offered by our test as a really good thermometer,” Terbrueggen said.

If the result is positive, companies would send home that person and anyone who had been in contact with the employee. “It’s an added expense, but it’s between that and having to close down your line,” Terbrueggen said, adding that the service should launch this week. The firm’s initial customers include a 40-person machine shop, a dairy farm and cheese producer, as well as large biotechnology and pharmaceutical companies.

Yet it remains unclear whether diagnostics such as DxTerity’s test will work well enough to provide comfort to employers and workers. DxTerity is among dozens of companies seeking the Food and Drug Administration’s emergency use authorization, which allows unapproved medical tests to be put into use.

At Whirlpool, company officials held a conference call on Friday to discuss how best to bring back workers who weren’t deemed essential a month ago. The company has several thousand employees at its headquarters and at factories in Michigan and Ohio who are complying with stay-at-home orders. The company closed a plant for about two weeks in Amana, Iowa, after two workers tested positive. One issue when all employees return: whether to use infrared cameras to detect elevated body temperatures, which would be faster than using individual thermometers. Temperature checks still wouldn’t flag workers who are carrying the virus and contagious but show no symptoms.

“We are exploring technology solutions to allow employees to pre-certify that they are without symptoms before they come to work and to monitor the availability of rapid response covid-19 tests, providing our employees even greater peace of mind as they return to work,” a company spokesman said in an email.

Last week, the online retail giant Amazon announced that it had “begun the work of building incremental testing capacity” so that it could test employees who work in its warehouses and shipping facilities.

“If every person, including people with no symptoms, could be tested regularly, it would make a huge difference in how we are all fighting this virus,” the company wrote in a blog post. “Those who test positive could be quarantined and cared for, and everyone who tests negative could re-enter the economy with confidence.”

But Amazon, where at least 64 employees have fallen ill with covid-19, acknowledged that regular testing is unrealistic given the current scarcity of tests. It noted that the testing capacity it is building may not come into full operation before the immediate outbreak subsides.

And an antibody test that is reliable, affordable and available remains elusive.

“For workers in high-risk jobs with lots of contact with others or contact with high-risk people, it will be appealing to make sure that they are immune to reinfection if antibodies are protective. This will lead employers and the government to want to put in place widely available testing for antibodies," Kocher said. “The hitch is that high-quality, low-cost and plentiful antibody tests are not available yet in America.”

And if they are developed, the tests will remain “notoriously hard to develop with real challenges with both false-negative and false-positive results,” Kocher said. “Both of these flaws are problematic since false negatives keep people out of the workforce and false positives put people at risk.”

Unions are also wary of a large-scale return to work. “There isn’t adequate testing for people already at work, so the thought of bringing more people back when they don’t have those safety measures in place is really shortsighted,” said Rebecca Reindel, a health expert at the AFL-CIO. She warned that “in other countries when people go back to work, the number of cases goes up again.”

Some businesses and governments have hired data analytics firms to help guide them through key decisions.

SparkBeyond is an Israeli-based start-up that is advising major consumer-goods firms as well as the governments of Argentina, Israel and Italy on navigating the outbreak — and detecting patterns of spreading disease. In Italy, for example, the firm identified that not only were gas stations, water fountains and railways key infection sites, but that the A1 highway running from Milan to Naples also became an artery of contagion as people drove from north to south.

For businesses that need to ship goods, understanding the relative risks of transportation routes remains critical. And the same goes for policymakers looking to open up some economic sectors or parts of their city and state.

“You can provide a risk indicator in real time,” SparkBeyond’s chief commercial officer Amir Haramaty said, though he added that the data will have to be reanalyzed constantly. “This is dynamic. This is information that can give you a 72-hour window about what’s coming up next.”

And that kind of ongoing data stream about human infection poses privacy concerns.

Concealing sensitive personal information remains critical, Haramaty said, adding that his company uses what it calls “blindfolded analytics” so that no human data scientist can see that sort of information.

“The line between use and abuse is very fine,” he said, referring to sharing personal location information and other data. “There’s no excuse, and we’re going to regret it for the rest of our lives if we open the floodgates.”

Some say making Americans feel safe again requires wide-scale testing by the public health system, not just private employers.

Scott Gottlieb, former head of the FDA, said that coronavirus testing should be as common as tests for strep throat. He said that covid-19 tests should be done at every one of the 3.8 million weekly visits Americans make to their doctors’ offices, not just when people show symptoms.

“It sounds ambitious to say everyone who presents to a physician should get swabbed, but it’s not an unacheivable goal,” Gottlieb said. “We’re now testing 1 million people a week. So getting to 4 million a week is an achievable goal.”