Twitter has closed its San Francisco and New York offices amid surging COVID cases.

A return to the office will have to wait, at least for Twitter employees, as the company is shuttering offices and delaying any further openings.

“After careful consideration of the CDC’s updated guidelines, and in light of current conditions, Twitter has made the decision to close our opened offices in New York and San Francisco as well as pause future office reopenings, effective immediately,” a Twitter spokesperson said, according to CNBC.

Much of the blame lies with the Delta variant of COVID, which is far more contagious and has even been infecting some vaccinated individuals. As Twitter acknowledged, the CDC has been forced to update its guidelines in an effort to combat the aggressive variant.