For much of the pandemic, a familiar ritual played out in America’s workplaces: Companies set return-to-office dates, only to later backtrack and delay them due to health concerns.

With Covid-19 cases on the rise once again and U.S. authorities warning of a potential surge in infections this winter, employers find themselves questioning their approaches again.

Companies...

For much of the pandemic, a familiar ritual played out in America’s workplaces: Companies set return-to-office dates, only to later backtrack and delay them due to health concerns.

With Covid-19 cases on the rise once again and U.S. authorities warning of a potential surge in infections this winter, employers find themselves questioning their approaches again.

Companies like Apple Inc. are delaying January office returns, while others say they are sticking with their reopening targets. Some, like Salesforce.com Inc., are abandoning dates altogether and urging managers to find ways to meet with their teams in the coming weeks. A few, like Allstate Corp. , are telling the vast majority of workers they can stay remote permanently, while keeping some offices open for those who want to gather.

The varied strategies reflect much continued uncertainty about the pandemic’s trajectory, along with the unclear fate of the Biden administration’s vaccine and testing mandate that has been temporarily blocked by a federal appeals court.

A shift in thinking is also coloring corporate decisions. Many executives increasingly say that companies, like society, might need to better live with a virus that shows no sign of disappearing. They say that means moving forward with office reopening plans or managing alternate arrangements to get teams together.

Levi Strauss & Co.’s innovation lab. The company broadly reopened its San Francisco headquarters to workers on a hybrid basis in October.

Photo: David Paul Morris/Bloomberg News

“The pandemic is not over. It’s moving into an endemic,” said Brent Hyder, president and chief people officer of Salesforce. “The ‘return-to-office’ dates, for me, are irrelevant. I don’t understand them. We need to find ways to meet safely.”

Salesforce has more than 65 open offices around the world for those who want to use them, but it has also embraced flexible and remote working, giving many teams a choice of where and how they do their jobs. As the pandemic has stretched on, many employees have signaled in company surveys that they want some in-person time with their colleagues, even if that is brief or once a quarter. That has led to in-office meetings in places like New York or San Francisco, but also outdoor gatherings in a backyard and off-site meetings in Arizona, Mr. Hyder said.

Many executives fear that the longer remote work lasts, the greater toll it can take on company culture, even as employees successfully do their jobs at home. Bosses worry staffers could become disconnected from the company without some face-to-face interaction with peers from time to time. “We have to connect as humans, and we do our best work when we figure out how to do that,” Mr. Hyder said.

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Rather than force people back to offices, many companies have at least initially reopened corporate campuses on a voluntary basis, concluding that it is better to encourage people to return to in-person settings. Such a strategy is also meant to ease the transition to commuting and working next to peers in offices again, human-resources executives say.

Across the U.S., plenty of offices remain fairly empty, particularly in big cities, though occupancy has been rising in recent weeks. Offices in 10 major U.S. cities were on average 39% occupied in the week ended Nov. 10, a pandemic-era high, according to Kastle Systems, a security company that tracks access-card swipes in thousands of buildings.

At denim maker Levi Strauss & Co., the headquarters in San Francisco broadly reopened on a hybrid basis on Oct. 25. Many corporate employees generally work two or three days a week from the office, though schedules vary based on employee and team needs, a spokeswoman said.

In Europe, where cases have surged in recent weeks, the situation is different. Authorities in Belgium mandated recently that employees work four out of five days from home, affecting a large Levi office in Brussels.

A broad swath of workers remain nervous about getting sick at work. In a September survey of 2,000 U.S. workers commissioned by the insurer Prudential Financial Inc., 70% of remote workers said they worried about catching or spreading Covid-19 when returning to an office. While the outcomes for vaccinated people generally are more mild, having the illness can be disruptive, and vaccinated people can spread the virus, including to unvaccinated people at risk of worse outcomes.

A number of prominent U.S. employers that set January 2022 office return dates so far haven’t announced changes, though many companies noted that they closely watch local case rates and regulations and could still adjust course. Representatives for Wells Fargo & Co., Alphabet Inc.’s Google and Facebook owner

Meta Platforms Inc. said they were still working toward planned office returns in January.

Apple has delayed its return-to-the-office plans several times. The most recent came Nov. 18, when Chief Executive Tim Cook told employees in a memo that they would return in a hybrid approach in February instead of January. The company aims to use a phased-in return one or two days a week for a month, then in March have workers in the office three days with the option for remote working on Wednesdays and Fridays.

Large private employers must ensure that their workers are vaccinated or tested weekly for Covid-19, according to a Biden administration mandate set to take effect Jan. 4. WSJ’s Sarah Chaney Cambon explains what you need to know about the new rules. Photo: Susan Walsh/Associated Press The Wall Street Journal Interactive Edition

Some companies had earlier pushed back office reopening dates, wanting time to comply with the Biden administration’s vaccine or testing mandate. Those rules, set to take full effect in early January, have been temporarily blocked by a federal appeals court. The Occupational Safety and Health Administration said on Nov. 17 that it remains “confident in its authority to protect workers in emergencies,” but said it has suspended enforcement of the new rules pending developments in the litigation.

Some companies predict parents will feel better coming back to corporate campuses once their children are inoculated. The U.S. recently approved one of the vaccines for use in children as young as 5 years old.

Genentech, a division of drugmaker Roche Holding AG , expects most of its employees to return to its headquarters near San Francisco on a hybrid schedule beginning in January. Even before that date, though, more parents might begin working from the office voluntarily as they get their kids vaccinated, said Cynthia Burks, the company’s chief people and culture officer.

“I really do think we’ll start to get more of an uptick of people coming to campus,” she said, as parents feel “more comfortable about their family situation.”

What also remains unclear is what this winter holds. Dr. Anthony Fauci, the Biden administration’s chief medical adviser, said at a conference last week that the U.S. could be in for a “double whammy” of higher cases among the unvaccinated and more breakthrough infections among vaccinated Americans, unless more is done to counter the virus.

He urged cities to keep masking guidelines and other mitigation measures in place. He said the trajectory of the pandemic in the coming months will depend on whether the roughly 60 million unvaccinated Americans get shots, along with the success of booster campaigns to help those already inoculated. “If we don’t do that,” he said at the STAT Summit, “I think we’re in for some trouble.”

—Tim Higgins and Ben Eisen contributed to this article.

Write to Chip Cutter at chip.cutter@wsj.com