Dec 30 (Reuters) - JetBlue Airways Corp is reducing its schedule through Jan. 13 by about 1,280 flights due to a surge in crew members falling sick from the Omicron coronavirus variant, a spokesperson for the airline told Reuters on Thursday. Carriers have been canceling hundreds of flights every day in the United States since Christmas Eve as they grapple with staff shortages due to COVID-19 infections and bad weather in parts of the country. Over 1,000 flights were canceled within, into, or out of the United States as of Thursday morning, according to flight-tracking website FlightAware.com. "We expect the number of COVID cases in the northeast – where most of our crew members are based – to continue to surge for the next week or two," JetBlue"s spokesperson said in an emailed statement. "This means there is a high likelihood of additional cancellations until case counts start to come down." COVID-19 cases in the United States have been hitting new highs in the past few days, with the average number of daily confirmed cases touching a new record of 258,312 over the past seven days, a Reuters tally showed on Wednesday. read more The U.S. Centers for Disease Control and Prevention earlier this week said it was not currently considering a vaccine mandate for domestic flights. It later shortened the recommended isolation time for Americans with asymptomatic cases of COVID-19 to five days from the previous guidance of 10 days. Delta Air Lines Inc (DAL.N) soon after updated its policies for workers testing positive for COVID-19 by providing them five days of paid leave to isolate, the New York Times reported on Wednesday, citing an internal company communication. The company is also encouraging, but not requiring, those workers to take COVID-19 tests to go back to work, according to the report. Delta did not immediately respond to a Reuters request for comment.