American Airlines Group Inc. expects to put most of its fleet back in service in the second quarter, following “recent strength in domestic and short-haul international bookings.”

Falling infections and hospitalizations and rising vaccinations have spurred demand after a blow early this year when the U.S. required negative coronavirus tests for international travelers, American said in a regulatory filing Monday. The seven-day average of net bookings on March 26 was about 90% of the 2019 level and domestic flights are 80% full, the company said.

American’s improved assessment indicated the progress made in recent weeks against a pandemic that caused an unprecedented decline in travel last year. The Fort Worth, Texas-based company projected that bookings strength would continue through the end of the month and into the second quarter, but cautioned that visibility was limited.

The demand outlook for long-haul international flights is also cloudy. Much of Europe is lagging behind the U.S. in vaccine distribution, and some countries have recently imposed more restrictions on movement and gatherings.

American was little changed at $22.94 at 9:53 a.m. in New York. The shares had climbed 45% this year through March 26, the most on a Standard & Poor’s index of major U.S. carriers.

First-quarter system capacity will be down 40% to 45% from the same period in 2019, American said. That represents a slight improvement from the airline’s previous outlook of down 45%.