Citigroup told employees that they’ll need to get the Covid-19 vaccination before returning to its offices, becoming one of the only major U.S. banks to take that stance.

The move was announced Tuesday as part of the bank’s plans to bring more workers back to corporate offices in the New York area, as well as Chicago, Boston, Washington D.C. and Philadelphia, according to a LinkedIn post from the bank’s human resources head Sara Wechter.

Employees at those offices “will be expected to return at least two days a week and vaccination is required” starting Sept. 13, Wechter said. “Given the increased number of employees returning to these buildings, and the delta variant in the U.S., we are taking this approach to ensure a safe workplace.”

Most large banks including JPMorgan Chase and Goldman Sachs recommend that their employees get vaccinated, but stop short of requiring it. One exception is Morgan Stanley: The bank told employees in June that those returning to its New York headquarters and other large offices need to be vaccinated.

The spread of the highly contagious delta variant of Covid-19 has roiled corporate plans to return more employees to the workplace, prompting some firms to mandate vaccines or push back return dates. Citigroup and JPMorgan recently brought back mask mandates for employees, regardless of vaccination status.

At Citigroup, employees working in corporate offices besides the ones mentioned will continue to work remotely, Wechter said. The bank “strongly” encouraged branch employees get vaccinated, according to Bloomberg, which reported the news earlier.

“These are our plans as of today, and I assure you if the facts change, we will too,” Wechter said.

This story is developing. Please check back for updates.