IBM, which nearly three years ago ended remote work for some U.S. employees, said Thursday it had asked workers in coronavirus-affected areas to work from home “wherever possible.”

The guidance, issued for IBM workers in China, Japan, South Korea and Italy, comes as companies scramble to protect their employees from the spreading virus by canceling conferences, making work-from-home arrangements overseas and designing contingency plans for U.S. locations.

The virus has exacted a deepening toll on world economies, with U.S. markets plunging sharply Thursday, in the worst four-day loss since the 2008 financial crisis.

IBM is “having our employees work from home where recommended and deciding on our participation in large meetings and trade shows on an individual basis,” company spokeswoman Laurie Friedman said in an email. She said the move was temporary and that it was “too premature for us to talk about consideration of a broader policy at this time.”

The company is also restricting travel to some locations and canceled its in-person participation in the RSA Conference on cybersecurity in San Francisco this week.

As concerns grow over the spread of the new coronavirus, which causes a respiratory illness called covid-19, other companies stepped up their precautions.

Goldman Sachs said it has restricted business travel to South Korea, as well as to the Lombardy and Veneto regions of Italy, and asked that nonessential business travel to other parts of Italy and Asia be postponed. In addition to mainland China, “all employees who have traveled to South Korea or the impacted regions in Italy, or who have been in close contact with individuals who have been to these areas, are required to remain out of the office for at least 14 days,” the company said.

PwC is asking employees to defer or cancel trips to Japan and is encouraging them to use the company’s $1,000 annual backup child-care benefit in case of school or day care closures.

Siemens said it “urgently recommend[s]” employees to replace nonessential travel to affected regions with phone calls or video conferences, and Coca-Cola said it has asked office workers in China, Singapore, South Korea and Italy to work from home.

The virtual currency exchange Coinbase even put its action plan up online, outlining what would “trigger” it to ask employees to work from home, enhance office cleaning schedules, or start a visitor health-screening program. “We hope to help other companies that are trying to navigate this situation and to encourage a calm, rational approach,” said Philip Martin, the company’s chief information security officer, in an emailed statement.

Over the past week, said Howard Mavity, who specializes in workplace safety and catastrophe management at the law firm Fisher Phillips, dozens of businesses have contacted his firm with questions. “They’ve now been asking for policies and procedures instead of one-off advice,” he said.

“Most employers can’t let everybody telework,” Mavity added. “What do you do if you’re in manufacturing, retail or hospitality?”

More companies are also skipping conferences and major corporate events. Facebook said Thursday it’s canceling its annual F8 developers conference, and Sony Interactive Entertainment and Facebook Gaming canceled appearances at the Game Developers Conference in March. The software company Workday canceled an annual internal sales meeting that was supposed to draw 3,000 people and is hosting a “virtual experience” instead, a company spokesman told CNBC.

While many professional workplaces and office environments may have had remote work arrangements for employees, and are equipped with laptops, smartphones and video conferencing tools, human resources experts say many others will face challenges if they have to implement remote work on a broad level. U.S. census data shows that fewer than 5 percent of workers who are not self-employed work from home at least half of the time.

“Do they know how to use the video conference? Can they share files remotely? Do they know how to create a group discussion with their teammates? What if their laptop fails — is there a help number they can call?” asked Kate Lister, the president of Global Workplace Analytics. “What companies should be doing right now is practicing. Start sending people home, start teaching them the protocols.”

Marc Cenedella, the CEO of the careers site Ladders, is planning to do just that. Next Thursday, he has planned for all 60 of his New York employees to work remotely on the same day. “No one’s coming into the office, and we’re keeping all our regularly scheduled meetings,” he said. One of the biggest hiccups he expects is his employees simply getting used to not having multiple computer monitors at their desks.

But he also recognizes it represents a different way of working. “There are a lot of assumptions about how a group of people work together that you never talk about and never write down.”

On Tuesday, officials from the Centers for Disease Control and Prevention, along with other agencies, urged businesses to make plans for how to limit the virus’s impact, raising questions about plans for remote work or the closure of schools or day-care centers.

Some note that many executives who are making contingency plans or decisions will be confronting a global outbreak for the first time. “SARS was in the early-2000s,” said Brian Kropp, the chief of research for Gartner’s human resources practice, referring to the spread of severe acute respiratory syndrome in 2003. When you just look at the percent of people who were executives now and were executives then, it’s really low numbers.”

David Barron, an employment lawyer with Cozen O’Connor in Houston who works with businesses, said that many companies are putting travel restrictions in place but that few in the United States are talking yet about arrangements for remote work. They are, however, discussing what they’ll do if the virus’s spread causes widespread absences, such as letting workers dip into the following year’s paid time off bank.

He’s also watching how things are changing in real time. He was helping a large auto parts supplier put together a coronavirus response plan Wednesday when one manager had to step out of the meeting to talk with an employee in Britain whose wife had just received a coronavirus diagnosis. “From where things were a week or two ago, it’s like a different world,” Barron said.