Southwest Airlines doesn’t serve Asia or Europe, but that doesn’t mean the nation’s largest domestic carrier is immune from coronavirus travel fallout.

The airline has seen a “very noticeable, precipitous decline in bookings” in the past week, a decline that continues daily, CEO Gary Kelly said in an interview with CNBC on Thursday.

“It’s really all of a sudden,” he said, noting that Southwest’s ticket sales were solid through February, before the coronavirus spread broadened and intensified. .

The drop-off in new bookings plus an increase in cancellations was so dramatic Southwest warned investors about it Thursday, saying its first quarter revenue will be down an estimated $200 million to $300 million from previous expectations.