United Airlines plans to reduce its number of flights due to a shortage in resources and staff. CEO Scott Kirby said in a memo to staff Monday that the company will be "reducing our near-term schedules to make sure we have the staffing and resources to take care of customers.”

The announcement comes as United has around 3,000 workers, or 4% of its workforce, unavailable due to testing positive for COVID.

"I also know that Omicron has affected the personal well-being of our United team. We have about 3,000 employees who are currently positive for COVID," said Kirby.

Kirby noted that the vaccination mandate has helped prevent hospitalizations for employees.

"The second and most important piece of good news is that our vaccine requirement is working — and saving lives. While we have about 3,000 employees who are currently positive for COVID, zero of our vaccinated employees are currently hospitalized," Kirby said.

United Airlines' decision follows other airlines, like JetBlue Airways and Alaska Airlines, that have seen similar issues due to the spread of the Omicron variant. JetBlue was the first to trim its schedule when it announced last week that about 3,000 JetBlue employees tested positive for COVID.

American Airlines said that it would also reduce its schedule if its COVID rates continue to rise.