- United posted a $1.9 billion loss for the fourth quarter.
- CEO Scott Kirby said a "critical mass" of people need to be vaccinated before there's a recovery.
- Kirby remained cautious about a recovery in air travel and declined to project when the carrier will break even.
United Airlines shares tumbled more than 5% on Thursday after warning a recovery in travel demand is still months away.
CEO Scott Kirby said Thursday that many more people need to receive coronavirus vaccines before travel demand returns, highlighting difficult months ahead for the industry. The airline posted a $1.9 billion loss after the market closed on Wednesday, marking its fourth quarterly loss in a row.
"Until we can put as a society coronavirus in the rearview mirror, it's going to continue to be a tough environment for aviation for everyone who's involved in travel, tourism and leisure," Kirby said in an interview on CNBC's "Squawk Box."
The vaccine rollout has been slower than expected, raising questions about when the pandemic will be brought under control.
Kirby said it's too early to tell when the carrier will break even. Competitor Delta Air Lines said last week it expects to break even by the spring.
"We really need to get a critical mass of people in the country vaccinated, and we also need a scientific medical conclusion that it not only protects you from the virus when you get vaccinated but also protects you from transmitting the virus," said Kirby.
United was upbeat about long-term travel demand, however. On Wednesday, the carrier said it expects to surpass its pre-pandemic margins by 2023.