Leading airline and business groups are asking the Biden administration to develop temporary credentials that would let travelers show they have been tested and vaccinated for COVID-19, a step that the airline industry believes will help revive travel.

Just how bad was 2020 for the airline industry? The six biggest U.S. airlines lost $34 billion, and Southwest suffered its first full-year loss since Richard Nixon was president and gasoline sold for 36 cents a gallon.