China has canceled over two dozen scheduled flights from the United States in recent weeks after multiple passengers tested positive for COVID-19 upon arrival.

China's aviation regulator has required the cancellation of eight planned passenger airline flights from the United States to Shanghai under its COVID-19 pandemic rules: four by United Airlines and two by Delta Air Lines and American Airlines.

Delta said it halted Detroit-Shanghai flights last Friday and January 14 in response to a Chinese regulation mandating "all affected carriers" with passengers who test positive for COVID-19 to "to cancel inbound service on certain China flights."

Additionally, the Chinese Civil Aviation Administration has canceled at least 22 other flights to the United States operated by Chinese carriers since December following positive COVID-19 tests, including eight by China Southern Airlines Co.

The United States is experiencing an outbreak of illnesses caused by the highly contagious Omicron variety, with 132,646 persons hospitalized with COVID on Monday, breaking the January 2021 record of 132,051. The seven-day average for new cases has more than doubled to 704,000 in the last ten days.

United announced that it was forced to cancel flights from San Francisco to Shanghai on January 15, 19, 22, and 26. The Chicago-based carrier flies four times weekly between San Francisco and Shanghai.

The United States Department of Transportation did not immediately respond to a request for comment late Monday.

Chinese-American air services

China and the United States have been at odds over aviation services since the COVID-19 epidemic.

In August, the USDOT restricted four flights operated by Chinese carriers to 40% passenger capacity for four weeks after Beijing imposed similar restrictions on four United Airlines flights.

China informed United in August that it was placing restrictions on some flights following an allegation that five passengers traveling from San Francisco to Shanghai on July 21 tested positive for COVID-19.

In August, the USDOT stated that China's regulation "places undue culpability on carriers with respect to travelers that test positive for COVID-19 after their arrival in China."

According to the department, carriers "have no means to independently verify positive test results alleged by Chinese authorities."

A long-standing agreement between the United States and China provides for over 100 weekly flights between the two countries. However, only a handful of those is currently operational.

In January 2020, former US President Donald Trump banned practically all non-US citizens from traveling to the United States if they had been in China within the previous 14 days.

In November, President Joe Biden removed Chinese travel restrictions on properly vaccinated international flight travelers.