Delta Air Lines has pledged to keep the middle seat blocked until early-2021.
However it will increase overall capacity in economy from the current 60% to 75%.
"Medical experts, including our own partners at Emory Healthcare, agree — more distance on board makes a difference," said Bill Lentsch, Delta’s head of customer service.
It will make available more aisle and window seats and let families book seats next to each other beginning on 1 October.
The airline said maximum capacity in the first-class cabin will stay at 50% until 31 October.
"Restoring confidence in the safety of air travel is more important right now than filling up every seat on a plane," Lentsch said.
The new capacity limit in economy will be evaluated again in October and may be amended further.
Written by Ray Montgomery, US editor
