JetBlue Airways Corp. will join other major U.S. carriers in opening up previously blocked seats, citing increased evidence that cabins are safer from the spread of coronavirus than many indoor environments.

Starting Jan. 8, the airline will make all seats available for sale, JetBlue President Joanna Geraghty told employees in a memo Thursday. It joins Southwest Airlines Co., which will free up seats after November, and Delta Air Lines Inc., which plans to make all seats available after Jan. 6.

Carriers have moved away from keeping seats off limits—which had been intended to provide social distancing and to reassure passengers—as travel demand has increased and cabin cleaning has improved.

Some recent studies, including by Harvard’s T.H. Chan School of Public Health and by the U.S. Defense Department, have shown the chance of coronavirus transmission on board “is extremely low,” aided by hospital-grade air filters, JetBlue said.

“Our phased approach has offered a thoughtful path forward while giving us the time needed to understand the science and stay true to our #1 priority—safety,” Geraghty said.

Airlines, which are losing millions of dollars a day as travel remains depressed by the coronavirus and changing travel restrictions, had said it wouldn’t be financially feasible to hold open seats indefinitely.