CHICAGO (AP) — United Airlines lost $646 million in the fourth quarter and said Wednesday that the current spike in COVID-19 cases will hurt its results in the March quarter.

The airline said it expects its first-quarter revenue will be down 20% to 25% from the same period in 2019. Costs other than fuel will rise about 15% on a per-seat basis.

The omicron variant of the virus is showing up in United’s plans for 2022. The airline had once hoped to operate 5% more flights than it did in 2019, but now expects to fly less this year than it did before the pandemic.

United said omicron is hurting near-term bookings, but the outlook is better for travel in spring and summer. The Chicago-based airline said it is on track to hit long-term financial targets for 2023 and 2026.

Company officials are scheduled to discuss the results with analysts on Thursday.

United’s fourth-quarter loss compared with a loss of $1.9 billion a year ago and profit of $641 million in the fourth quarter of 2019.

Excluding special items, the company said its adjusted loss was $1.60 per share. Analysts expected a wider loss of $2.09 per share, according to a FactSet survey.

Revenue was $8.19 billion, 25% below the same period in 2019 but better than the $7.96 billion forecast by analysts. Passengers flew 28% fewer miles than they did two years earlier.

United lost $1.96 billion for all of 2021, even after getting $4 billion in federal pandemic relief to help cover labor costs.

The airline finished the year with 84,100 employees, down from 95,900 at the end of 2019.

Shares in United Airlines Holdings Inc. were down about 2.4% in extended trading following the release of the earnings report.