Finnair Oyj said the coronavirus outbreak has led to so many flight cancellations that it’s taking about a month to refund passengers.

The delays, revealed in a tweet, show the scale of the challenge the epidemic poses for airlines as routes are cut, companies halt business trips, governments limit entry and people increasingly decide just to stay home.

For Finnair, the virus has been especially disruptive after it built Helsinki into a hub for travel to east Asia, utilizing the shortest flight times from anywhere in Europe. Among measures in the region, the carrier has canceled services to China and Seoul and cut frequencies to Hong Kong and Osaka, Japan.

Finnair customers headed elsewhere are now allowed to postpone travel at no extra cost, or get a full refund if they cancel by March 31.