China is demanding that some travelers arriving from abroad do an invasive anal smear test as part of their coronavirus containment measures, a measure that outraged and shocked several foreign governments.
Japanese officials said on Monday that they had formally asked China to exempt Japanese citizens from the test, adding that some of those who received it complained of “psychological distress”. And the United States Department of State said last month that it filed a protest with the Chinese government after some of its diplomats were forced to undergo anal smears, although Chinese officials deny it.
It is unclear how many swabs were administered or who is subject to them. Chinese state-run media acknowledged that some arrivals in cities like Beijing and Shanghai are likely to take the tests, although reports say requirements may vary depending on whether travelers are considered to be at high risk.
Chinese experts have suggested that traces of the virus may survive longer in the anus than in the respiratory tract and that samples from the former may prevent false negatives. China has imposed some of the world’s most stringent containment measures, including barring most foreign arrivals, and has largely suppressed the epidemic.
Lu Hongzhou, an infectious disease specialist at Fudan University in Shanghai, told the state tabloid Global Times that nasal or throat smears can cause “uncomfortable reactions”, leading to below-average samples. He acknowledged that fecal samples can replace anal swabs to prevent similar discomfort.
But other experts – including in China – questioned the need for anal samples. The Global Times quoted another expert, Yang Zhanqiu, as saying that nasal and throat swabs are still the most effective because the virus is contracted by the respiratory tract.
Benjamin Cowling, a professor of public health at the University of Hong Kong, said in an interview that even if someone tested positive on an anal smear but not a respiratory smear, it probably wouldn’t be very contagious.
“The value of detecting people with the virus is to stop transmission,” said Professor Cowling. “If someone caught an infection, but it is not contagious to anyone, we don’t need to detect that person.”
A spokesman for the Chinese Foreign Ministry said this week that the government would make “science-based adjustments” to its containment policies.
Professor Cowling said he did not know what was the scientific basis behind the existing policies. “I assume there is some evidence leading to this decision, but I have not seen that evidence,” he said.