But CDC also notes that most viruses and other germs don’t spread easily on flights because of how air circulates on planes.
Standard & Poor’s said this week that the industry’s prospects have gone “from bad to worse”, with global air traffic dropping by up to 70 percent this year.
In May, S&P said a 55 percent drop was a worst-case scenario.
“It’s going to be a slower and more uneven recovery than one might have expected,” S&P analyst Philip Baggaley said.
An airline trade group, the International Air Transport Association, predicts carriers will lose $84 billion this year, making it the worst year in the industry’s history.
The group says traffic won’t fully recover until 2024.
Asia, where outbreaks were brought under control earlier, is doing better than the US and Europe.
Read also: EU Travelers Have Advantage of Loosened Travel Restrictions in China
Domestic travel inside China has recovered to about two-thirds its year-ago level. In the US, traffic is less than one-third of 2019 levels.
Air traffic at Europe’s more than 500 airports has tumbled, down 94 percent in June compared with the same month last year.
There were about 4 million passengers, compared with 217 million a year earlier.
Travel ticked up when more than two dozen European countries opened borders to one another in early July, but virus cases are rising in several countries, leading to reimposed restrictions.
This week, the UK imposed a 14-day quarantine requirement on travelers — even Britons returning home — from France and the Netherlands.
Read also: France and the Netherlands Added to Mandatory UK Quarantine List
Travel from outside Europe, including the United States, is still restricted.
In the United States, traffic picked up after collapsing by 95 percent in April but has stalled — down 74 percent in July, 72 percent in August.
Airlines came into this crisis in the best shape ever financially, thanks to rising demand for travel, reduced competition through mergers, and billions raised by extra fees.
Among international carriers, the big state-backed airlines are almost certain to survive. In Asia and the Middle East, they are often seen as vital contributors to the overall economy.