Delta Air Lines (DAL -0.58%) said Thursday it has extended its policy of blocking middle seats at least through the holidays, part of the airline's effort to differentiate itself and win back travelers scared off by the coronavirus pandemic.

Delta is modifying its policy slightly. The airline will begin to allow parties of three or more to book middle seats to allow families to sit together. But for parties of one or two, middle seats will be blocked to allow for greater distancing during flights.

"Medical experts, including our own partners at Emory Healthcare, agree -- more distance on board makes a difference," Delta's head of customer experience, Bill Lentsch, said in a statement. "We believe that taking care of our customers and employees and restoring confidence in the safety of air travel is more important right now than filling up every seat on a plane."

A Delta plane parked on the tarmac.

Image source: Delta Air Lines.

Delta and other airlines have been grappling with demand issues since the start of the pandemic. Even as states have lifted stay-at-home orders, travelers have been slow to return, in part because of the perceived dangers of contracting the virus at airports or on planes.

The entire industry has tried to entice passengers back by waiving change fees, requiring masks, and talking up cleaning procedures, but Delta's approach on seating is far from universal. The airline is one of only four U.S. carriers still restricting cabin capacity, and the other three -- Southwest Airlines, Alaska Air Group, and JetBlue Airways -- so far have only announced plans through October.

Delta last week said it was partnering with CVS Health to test flight crews for COVID-19 more regularly. The airline appears to be hoping that as families weigh traveling home for the holidays, the extra focus on safety will make Delta a more appealing option.

"We'll continue taking a thoughtful, layered approach ensuring customers know to expect the highest standard of care as they prepare for their holiday travels," Lentsch said.