Washington, Jan 13 (IANS): The highly contagious Omicron coronavirus variant has driven up the latest wave of the health crisis in the US and added stress to the US airlines, some of which otherwise may have upside earnings, according to a recent Reuters report.

"A multifold increase in daily sick calls as well as a series of winter storms have led to mass cancellation of flights," said the report posted Tuesday.

Only in one day, nearly one-third of the United Airlines' staff in Newark City in the eastern US state of New Jersey asked for sick leave over the phone, the report added.

A spokesperson for JetBlue Airways Corp. also said that JetBlue has seen "a surge in the number of sick calls," while warning of more fight cancellations until Covid-19 cases start to drop, according to the report.

Since Christmas Eve, US airlines have cancelled more than 30,600 flights, about 7 per cent of their scheduled total, one of the biggest disruptions in recent years, the report said, citing flight-tracking service FlightAware.

To mitigate the staff shortage, US airlines are offering incentives or deploying their management personnel to staff frontline operations, Xinhua news agency reported.

However, the incentives, along with flight cancellations, might further increase the airlines' costs.

The problems brought up by the lastest coronavirus wave have dampened the expectations of upside earnings for some airlines, the report added.