China requires some travelers arriving from overseas to undergo an invasive anal swab test as part of the coronavirus controls, a move that has angered 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 who had received it were complaining about ‘psychological distress’. And the U.S. State Department last night said it had registered a protest with the Chinese government after some of its diplomats were forced to undergo anal swabs, though Chinese officials denied the allegations.
It is not clear how many such swabs were administered or who is subject to them. The Chinese state media has acknowledged that some arrivals to cities, including Beijing and Shanghai, have to take the tests, but according to the reports, the requirements may differ depending on whether the travelers are considered a 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 of the former may prevent false negatives. China has introduced some of the strictest controls in the world, including blocking most foreign arrivals, and has largely suppressed the epidemic.
Lu Hongzhou, a specialist in infectious diseases at Fudan University in Shanghai, told the state-run tabloid of the Global Times that nose or throat swabs can cause “uncomfortable reactions”, which can lead to sub-samples. He acknowledged that fecal samples could replace anal swabs to prevent similar discomfort.
But other experts – including in China – question 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 transmitted through the airways.
Benjamin Cowling, a professor of public health at the University of Hong Kong, said in an interview that even if someone is positive on an anal swab but not a breathing problem, he or she is unlikely to be very contagious.
“The value of detecting people with the virus is to stop the transmission,” Professor Cowling said. “If someone has an infection but no one else is infected, we do not need to detect the person.”
A spokesman for the Chinese Foreign Ministry said this week that the government would make “scientific adjustments” to its delivery policy.
Professor Cowling said he did not know the scientific basis for the existing policy. “I assume there is evidence leading to this decision, but I have not seen the evidence yet,” he said.