U.S Companies reopening offices are trying to find out how much of their work force is vaccinated.

The message from many companies to their office workers is clear. It will soon be time to shed the slippers for hard shoes and return to your desk. But many companies are still puzzling over a single quandary: What to do about vaccines. Should they require employees to get them? Encourage or cajole or bribe them?

“We’re all kind of, you know, flying by the seat of our pants,” said Wayne Wager, the chief executive of Remote Medical International, a consulting firm in Seattle that is helping companies that are reopening offices. Mr. Wager said his own company had not decided what to do yet, but would probably demand that anyone coming back be vaccinated.

Most companies are hoping to avoid requiring vaccines. The federal agency that enforces workplace discrimination laws says they can, but chief executives fear vaccine mandates would lead to lawsuits, invite political upheaval and be hard to enforce. But they’re worried about safety. An outbreak could force a company to retrench on masking and social distancing policies, making it even harder to get back to normal. So they are trying everything short of a mandate, without yet ruling one out.

Nearly a third of companies have yet to develop any vaccine policy, according to a survey of 770 companies conducted by the human resources software company Tinypulse.