HOUSTON (KIAH) — Several hundred flights have already been canceled nationwide. Globally, airlines have canceled more than 6,000 flights on Christmas Eve, Christmas Day, and the day after Christmas.

Twelve percent of JetBlue flights, 6% of Delta Air Lines flights, 5% of United Airlines flights, and 2% of American Airlines flights have been canceled this weekend.

United, Delta and Jetblue say the cancellations are due to airline staff testing positive for the omicron variant. Lawmakers are calling on the CDC and the Federal Aviation Administration to make a major change and require proof of vaccination or a negative COVID-19 test to travel on all domestic flights.

Currently, the only state requiring a COVID negative test to enter is Hawaii.

Airlines are offering flight vouchers for those who had a canceled flight. Flight cancellations and delays are to be expected this entire week.