NEW YORK, July 12 (Reuters) - After more than 16 months of working from home, some Twitter Inc (TWTR.N) employees in San Francisco and New York returned to the office on Monday as the company reopened its corporate campuses at 50% capacity in the two cities. With COVID-19 vaccination rates on the rise, major U.S. tech companies are diverging on how and when to reopen their offices. Alphabet Inc"s (GOOGL.O) Google announced employees can voluntarily return to the office starting in late July, while Apple (AAPL.O) expects employees to work from the office three days per week starting in early September. Twitter employees shared pictures of their breakfasts and unmasked selfies in the elevator. One employee, referencing the food and music at the social media firm"s San Francisco office, wrote on Twitter, "I am more stoked than I expected to be." While some employees expressed excitement, most want minimal time in the office. An internal company survey found that 45% of employees in San Francisco and 63% in New York intend to return to the office, even if just one day per week. The remaining intend to keep working remotely. Twitter, which announced in May 2020 that employees could work from anywhere, is requiring proof of COVID-19 vaccination for office reentry. The company is still allowing employees whose jobs can be done remotely to work from home indefinitely. Twitter CFO Ned Segal said in a tweet that the company hopes to support employees "whether on their sofa or in an office." Twitter will continue to adjust employees" salaries based on cost of living in their location - a consideration for those who choose to work remotely. Facebook and Google have also reaffirmed their commitment to location-based pay policies. Twitter will decide when to reopen other offices based on COVID-19 infection and vaccination rates in each location, according to the company.