US airlines are canceling flights to and from Hong Kong after the city said it would require all crew members to be tested for Covid-19 upon arrival. American Airlines\n \n (AAL), which had been scheduled to resume flights from Dallas to Hong Kong on Thursday, will now restart on August 5. “We’ve been making regular adjustments to our schedule to match demand, and we consider a range of factors including travel restrictions or entry requirements in making network decisions,” the airline said in a statement. United Airlines\n \n (UAL) said it would suspend flights scheduled through Friday while it assesses how the new tests will affect its operations. The changes follow the announcement earlier this week that crew members would be required to submit deep throat saliva samples at Hong Kong International Airport. Crew members are currently exempt from a mandatory 14-day quarantine. The cancellations are another knock to efforts to get the world economy up and running again, restricting travel to a key financial hub. And they come as airlines express concerns about the future. United has warned nearly half of its frontline workforce that they could be furloughed this fall due to the slump in demand. Hong Kong, which has been praised for its quick and effective response to the pandemic, is now racing to keep a lid on infections amid a surge in local transmission. Health officials reported 42 new cases on Thursday. Starting at midnight Friday, restaurants won’t be allowed to operate at more than 60% capacity, and no more than eight people will be allowed per table. At clubs and bars, people will not be allowed to gather in groups of more than four. — Michelle Toh and Eric Cheung contributed reporting.