New York CNN  — 

Dozens of Jefferies employees have tested positive for Covid-19, forcing the Wall Street firm to ask staff to work from home, stop virtually all travel and cancel social events.

“Our priority now is to best protect every one of you and your families,” Jefferies (JEF) CEO Rich Handler and president Brian Friedman wrote in a memo to employees Wednesday.

The investment bank said that since the start of December, it has experienced nearly 40 new Covid cases. Tuesday alone saw 10 cases, causing nearly 50 employees to quarantine until they test negative.

Jefferies is based in New York, but it has nearly three dozen offices around the world, including in London and Hong Kong. The company did not specify where the infections occurred. A person familiar with the matter told CNN that the case total refers to a global figure.

Jefferies said that “with only a very few exceptions,” most of the cases have not required hospitalization. The bank pointed out that 95% of all employees are vaccinated and 100% of those who enter its offices are vaccinated.

As a result of the flurry of positive cases, Jefferies said employees will be encouraged to work remotely for the rest of December.

“When you can, we ask that you work from home,” the executives wrote.

Additionally, Jefferies said it will reimpose a mask mandate in all offices and require anyone who wants to enter any office or attend an event to have their booster administered by January 31, unless they are not yet eligible to do so.

“Effective today, we are canceling all social events and entertainment until January 3rd,” the executives said. “We will reassess then, and hopefully all will be better. All parties, big client functions and group events are now on pause. Additionally, all but the most essential business travel should stop, unless it is pre-approved. We are highly disappointed we need to take this step, but it is the prudent path forward to keep everyone as safe as possible.”

Just a day ago, JPMorgan Chase put out an optimistic outlook predicting that 2022 will be a year of a “full global recovery, an end of the global pandemic and a return to normal conditions we had prior to the Covid-19 outbreak.”

But the new health protocols at Jefferies underscore the difficulty businesses face as they try to get employees to work in person at a time of rising Covid cases and concerns about the new Omicron variant. Earlier this week, Ford delayed its return to the office for 30,000 workers because of Covid concerns.

“We strongly believe we are much closer to the end of this mess than the beginning,” the Jefferies executives wrote. “And thanks to all of you, we have achieved incredible success.”