Shares of U.S. airlines tumbled in premarket trading on Monday as a new fast-spreading COVID-19 strain in Britain renewed fears of widespread travel bans, with many countries barring flights from the United Kingdom ahead of the peak holiday season.

The news comes when U.S. carriers are burning $180 million in cash daily as passenger volumes remain down nearly 70% from year earlier levels due to the restrictions triggered by the pandemic.

Shares of Delta Air Lines shed about 7%, while those of American Airlines and United Airlines fell about 6%. Southwest Airlines dropped about 5% in premarket trading.

The new strain, said to be up to 70% more transmissible than the original, has prompted Canada, Germany, Italy and the Netherlands to suspend flights from Britain, while France has also barred freight carriers.

Investors also shrugged off the $15 billion in new payroll assistance for U.S. airlines, expected to be finalized on Monday, as part of a new coronavirus aid.

Shares of other U.S. travel companies too were lower on Monday.