United Airlines CEO Scott Kirby told the "TODAY" show on April 21 that the airline will be flexible with customers who are immunocompromised and who do not want to fly alongside passengers who are not wearing face coverings.

"All of our customers should feel free to wear a mask and many of them are," Kirby said. "For customers like that, that are immunocompromised or that have other concerns or issues … we are working with those customers if they really don't want to fly to find them another option, give them a credit, or if they just don't ever want to fly again, [we are] actually willing to give them a refund."

A United spokesman told The Associated Press that customers, except those on the lowest-priced "basic economy" fares are able to delay their travel plans for any reason without having to pay an extra fee. The spokesman added that passengers with special circumstances should call the airline's customer service number.