Delta has extended its move to block out middle seats, introduced to preserve and promote social distancing, until at least 30 March next year.
The airline said the move, which forms part of its "multi-layered" Delta CareStandard, offered travellers additional confidence and reassurance to book future travel plans.
Other aspects of the regime include advanced ventilation and an extensive cleaning programme, which Delta says "significantly reduce the risk of flight-related [Covid] transmission".
Delta chief customer experience officer Bill Lentsch added: "We recognise some customers are still learning to live with this virus and desire extra space for their peace of mind.
"We are listening and will always take the appropriate steps to ensure our customers have complete confidence in their travel with us.”
Delta said its CareStandard now encompasses more than 100 protective measures, including sanitising every flight and a comprehensive employee Covid testing programme.