In order to make sure that no potential carrier of the novel coronavirus goes amiss, China has started collecting samples for Covid-19 test from the anus.

The news comes a month ahead of the Lunar New Year holidays when tens of millions of people usually travel across states to celebrate the festival with their families, Aljazeera reported.

A city official in Weinan in northern Shaanxi province justified the process saying that a 52-year-old man, who was tested negative for the virus in nasal swab test, has tested positive in anal swab test.

For this test, health workers insert a cotton swab 3-5 cms (1.2-2inches) into the anus and gently rotate it to collect samples.

In a video posted by the newspaper Global Times , Zhang Wenhong of Huashan Hospital in Shanghai said that such swabs could be useful in helping minimise the risk of relapse after recovery.

“There may be traces of the coronavirus detected in the abdominal cavity faeces and intestine,” Zhang was quoted as saying in the report.

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Last week, a Beijing city official maintained that the state has collected more than 1,000 samples via an anal swab of teachers, staffers and students at a primary school in the city after an infection had been detected.

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 the upper respiratory tract, Dr Li Tongzeng, a respiratory and infectious disease specialist in Beijing city, told state TV last week, as cited in the Aljazeera report.

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Li added that these samples were only mandatory for high-risk groups such as those under quarantine.