Tech companies are bracing for a more aggressive COVID-19 outbreak as the new virus spreads across the United States. Several firms have called for employees to work from home to avoid the virus, but that's been a concern for contract workers, like bus drivers or cafeteria workers, who are paid by the hour.

Microsoft first announced Thursday to pay non-employees who provide services to Microsoft employees their normal hourly wages. On Friday, Facebook, Amazon, Twitter and Google confirmed to CNBC they're also committed to paying hourly workers regular wages despite a potential decreased need for services during a coronavirus outbreak.

"For contractors and hourly workers who are not able to perform their responsibilities from home, Twitter will continue to pay their labor costs to cover standard working hours while Twitter's WFH (work from home) guidance and/or travel restrictions related to their assigned office are in effect. All employees, including hourly workers, will receive reimbursement toward their home office set up expenses, and we are working with our vendors to ensure our contractors' WFH needs are met as well," a Twitter spokesperson said in an emailed statement.

Amazon confirmed to CNBC that the company will continue to pay all of its hourly employees in the Seattle area. This includes more than 10,000 people, the company said.

"We will continue to pay all hourly employees that support our campus in Seattle and Bellevue – from food service, to security guards to janitorial staff – during the time our employees are asked to work from home," an Amazon spokesperson said. "In addition, we will subsidize one month of rent for the local small businesses that operate inside our owned buildings to help support them during this period."

San Francisco health officials on Thursday confirmed two presumed positive COVID-19 cases in the city, which they believe is due to community spread. Facebook, Microsoft and Amazon have all confirmed at least one employee or contractor has tested positive for the virus in Washington state.

"We recognize the hardship that lost work can mean for hourly employees," Brad Smith, Microsoft's president and chief legal officer, said in a blog post. "As a result, we've decided that Microsoft will continue to pay all our vendor hourly service providers their regular pay during this period of reduced service needs. This is independent of whether their full services are needed."

-- Annie Palmer contributed to this report.

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