The Silicon Valley firm had already, in May 2020, become the first major tech company to allow staffers to work from home permanently, even after coronavirus lockdowns end.
On Wednesday it said it was closing its two largest offices.
'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,' the company said.
'We continue to monitor local conditions and make necessary changes that prioritize the health and safety of our Tweeps.'Insurance Loans Mortgage Attorney Credit Lawyer
The decision was made just two weeks after reopening the offices in both cities.
Jack Dorsey, the CEO of Twitter, pictured on June 4, has made the decision to close the two largest offices in his company. The San Francisco headquarters and New York offices will close immediately owing to a new surge in COVID-19 infections, from the Delta variant
The San Francisco headquarters of Twitter, where around a fifth of the company's 5,000 employees worked
Twitter's New York offices, in the Chelsea area of the city, will also close immediately
On Tuesday the Centers for Disease Control and Prevention (CDC) recommended that fully vaccinated Americans in parts of the country with 'substantial or high transmission' of COVID-19 should return to wearing masks indoors, citing new data on the highly contagious Delta variant.
The CDC also said masks should be required of everyone inside K-12 schools while urging classrooms to return to full-time, in-person classes 'with proper prevention strategies' in place.Insurance Loans Mortgage Attorney Credit Lawyer
The agency recommended that all vaccinated people consider wearing a mask if someone in their household was unable to be protected by the vaccine, like those with compromised immune systems or children who are too young to receive a shot, regardless of transmission levels in their community.
Jennifer Christie, Twitter's human resources chief, said in March 2020 that the company would 'never probably be the same' in its work culture post-pandemic.
'People who were reticent to work remotely will find that they really thrive that way,' she said.
'Managers who didn't think they could manage teams that were remote will have a different perspective. I do think we won't go back.'
Twitter had previously required employees to show proof of vaccination before returning, said Adrian Zamora, a Twitter spokesman, speaking to The San Francisco Chronicle.
The company is allowing employees to continue remote work permanently if they choose, but will maintain its office space.
Twitter's headquarters sits in San Francisco's Civic Center neighborhood, on the mid-Market corridor. The company moved in in 2012, and the offices house around 1,000 of their 5,200 employees.
Twitter's New York office, in the Chelsea district of Manhattan, opened with great fanfare in 2015. Around 400 people worked there according to reports, and celebrities such as Tom Hanks, Steven Spielberg and Donald Trump all toured the building.
Earlier on Wednesday both Facebook and Google announced that they will require its U.S.-based employees to be vaccinated against coronavirus before coming back to the office in October.
The vaccine requirement will be first imposed at Google's Mountain View, California headquarters and other US offices before being extended to the more than 40 other countries where Google operates
Facebook will require employees to be vaccinated before returning to the office
'How we implement this policy will depend on local conditions and regulations,' said Lori Goler, Facebook's vice president of people, on Wednesday afternoon.
'We will have a process for those who cannot be vaccinated for medical or other reasons and will be evaluating our approach in other regions as the situation evolves.'
Around half of the social media platform's 58,000 employees are expected to be working remotely when the offices open in October.
Earlier in the day, Google also said it was mandating its employees get vaccinated against COVID-19 when they return to campuses beginning in mid-October.
The date was delayed by a month due to the surge in cases nationwide fueled by the Indian Delta variant, the company announced.
In a Wednesday email sent to Google's more than 130,000 employees, CEO Sundar Pichai said the company is now aiming to have most of its workforce back to its offices beginning October 18 instead of its previous target date of September 1.
The decision also affects tens of thousands of contractors who Google intends to continue to pay while access to its campuses remains