▲Photo: Xinhua
Kashi in Northwest China’s Xinjiang Uygur Autonomous Region reported 61 new silent virus carriers on Saturday alone as it finished the second round of nucleic acid tests in key villages, sparking great concerns among the public about whether the initial clustered outbreak relating to a local clothing factory has spread in Xinjiang.
According to Xinjiang officials, among the 61 new infections, 46 cases are from Shufu county and the remaining 15 from two villages in Akto county in neighboring Kizilsu Kirgiz Autonomous Prefecture. All of them are people who had been put in quarantine at the beginning of the Kashi epidemic after a silent virus carrier was found on October 24.
As of Saturday afternoon, Xinjiang has reported a total of 273 COVID-19 infections – 51 confirmed and 222 asymptomatic infections, local health authority said at a press conference on Saturday.
Facing the rising infection number, Chinese experts reached by the Global Times on Saturday night said that these 61 COVID-19 infections could be a result of patients in incubation period or false negative nucleic acid tests, urging more thorough epidemiological investigation to detect the real source of infection – whether it began in Kashi Prefecture’s Shufu county or Akto county in Kizilsu Kirgiz Autonomous Prefecture.
Gu Yingsu, deputy head of the local health commission in Xinjiang, said at Saturday’s press conference that the 15 people from Kizilsu Kirgiz Autonomous Prefecture were tested negative in the first-round nucleic acid test but tested positive in the second-round test.
When Kashi rolled out the first round of citywide free tests, Kizilsu Kirgiz Autonomous Prefecture had also conducted citywide nucleic acid tests. The first round of nucleic acid tests in Kashi prefecture covering more than 4.7 million people was finished on Tuesday, according to Gu.
The second round of nucleic acid tests for residents living in Kashi and close contacts living in nearby villages of Kizilsu Kirgiz Autonomous Prefecture was completed within three days on Saturday, Gu said. Apart from those reported silent carriers and confirmed cases, all other residents tested negative for COVID-19, according to the official.
The rising infections not only in Shufu county but also in the neighboring villages of Kizilsu Kirgiz Autonomous Prefecture means the outbreak had already been spreading in those places, Zhang Yuexin, a member of Xinjiang’s anti-epidemic group, told the Global Times on Saturday. They must be close contacts of previous COVID-19 infections or close contacts of close contacts, but the patient zero is still unknown, Zhang said.
Wang Guangfa, a respiratory expert at Peking University First Hospital, also believes that since the source of infection in Shufu county remains unknown, whether it began in Shufu or Akto county is difficult to judge. “The place where epidemic was reported later could also be the source of origin, or one of the two branches of the same origin,” Wang said, emphasizing the importance of epidemiological investigation.
Wang suggested speeding up the epidemiological investigation and screening of cold-chain products and key population groups connected to the clustered infections in Shufu, which he believed is more effective than conducting massive nucleic acid tests.
Chen Xi, an associate professor of the Yale School of Public Health, also told the Global Times that tracking close contacts at this moment is critical. Suppress the spread at the community level so to avoid wider lockdown in the future, Chen noted.
Asked why those 61 COVID-19 infections were not detected in the first round of nucleic acid tests, experts and officials believed it could be a result of incubation period.
Gu said the incubation period of the novel coronavirus infected patients is one to 14 days, and the common incubation period is three to seven days, meaning that about 90 percent of people will test positive within three to seven days after infection, some in less than three days, and some people after more than seven days.
Chinese experts believed false negative nucleic acid tests also cannot be ruled out when they were first done. Repeated tests can prevent false negative test results.
Wang warned that asymptomatic patients are also contagious and if asymptomatic patients continue to be reported, it could mean a forgotten zone for anti-epidemic work. A thorough epidemiological investigation will plug the gap.
The COVID-19 infections will see gradual decrease in seven days and a noticeable decline in around 14 days, if the anti-epidemic measures are accurate and effective, Wang said, adding it needs several more days to tell whether the Xinjiang epidemic is being contained.