China rolls out anal swab Covid-19 test

China has begun using anal swabs to screen Covid-19 infections especially as the country heads towards Lunar New Year holidays.

Many squirmed at the idea that has been termed invasive but some health experts have lauded its accuracy.

A city official in Weinan in the northern Shaanxi province said a 52-year-old who exhibited Covid-19 symptoms initially tested negative for the virus but samples from the anal swab confirmed he was positive.

“Additional tests using anal swabs can pick up infections that other tests miss, as virus traces in faecal samples or anal swabs could remain detectable for a longer time than in samples taken from upper respiratory tract,” Dr Li Tongzeng, a respiratory and infectious disease specialist in Beijing city, said last week.

Anal swabs have been in use in China since last year, including in the major port city of Shanghai, but the method is so far reserved for individuals in potential Covid-19 hotspots.

"Since the start of the coronavirus outbreak, we've tested for the virus using mainly throat swabs. Its characteristics are convenience and speed, so it's suitable for large-scale testing," said Tongzeng.

Adding: "Nasal swabs are more accurate than throat swabs, but nasal swabs can be uncomfortable.

"In some asymptomatic cases or in individuals with mild symptoms, they tend to recover from the illness very quickly. It's possible that there will be no trace of the virus in their throat after three to five days.”

He reiterated that rectal swabs increase the rate of detectability and reduce the chances of misdiagnosis.

Last March, the Chinese Center for Disease Control and Prevention published instructions on how to go about the procedure and directed that a stool sample should be taken from patients, and if that is not possible, to do an anal swab by inserting a cotton-tipped stick three to five centimeters (one to two inches) into the rectum.

The procedure has continued to divide attention as some doctors argue that throat swabs are more effective since Covid-19 is a respiratory infection.