Tokyo has officially asked China to stop performing anal coronavirus swab tests on Japanese citizens, saying the test is causing them “great psychological pain”.
But Chinese health authorities are standing by the controversial testing regime.
Some authorities say “science-based” research shows anal swabs are more effective at detecting COVID-19 than nasal swabs.
The invasive procedure was introduced last month as part of strict new measures aimed at containing an expected surge in coronavirus cases around the time of Lunar New Year, when travel typically leaps.
An anal swab test involves inserting a cotton swab up to 5 centimetres into the rectum before gently rotating it several times, then removing it and placing into a sample container.
The entire process takes about 10 seconds.
Japanese chief cabinet secretary Katsunobu Kato said he was yet to hear back from Beijing officials after making a formal plea to stop the invasive testing method.
But Mr Kato said Japan would not let the issue slide, and will continue to pressure China to stop taking samples from the anus of Japanese citizens.
“Some Japanese reported to our embassy in China that they received anal swab tests, which caused a great psychological pain,” Mr Kato told a news conference.
He said the practice “has not been confirmed [to be effective] anywhere else in the world”.
The total number of Japanese citizens who have received the anal tests is unknown.
And they aren’t the only foreigners affected.
The procedure has also become a source of tension with the United States in recent weeks, after US diplomats told Washington they were forced to get the test.
China’s Foreign Ministry has firmly denied these allegations.
Thankfully, not everyone living in China has to get one.
Anal swab testing is reserved mainly for people living in areas with confirmed coronavirus cases, and those who have been quarantined, according to China’s state broadcaster CCTV.
Should we all be doing it?
Some health experts in China say the anal swab method is a more accurate way of testing for COVID-19 because traces of the virus linger longer in the anus than in the respiratory tract.
Li Tongzeng, a senior doctor from Beijing’s Youan hospital, told CCTV that an anal swab “can increase the detection rate of infected people”.
He said studies have found the virus can remain present in the stool of some infected people longer than it does in the upper respiratory tract.
Ramping up the use of anal swabs means less coronavirus cases would go undetected, he said.
Dr Li’s findings are backed by a paper published in September by researchers at the Chinese University of Hong Kong, who found that stool tests may be more effective than respiratory tests in identifying COVID-19 infections in children and infants because they carry a higher viral load in their stool than adults.
But that doesn’t mean Australians will be asked to follow suit.
Many health experts still believe nasal and throat swabs remain the most efficient coronavirus test.
That’s because COVID-19 is contracted via the upper respiratory tract and not the digestive system.