(Fighting New Coronary Pneumonia) Why are all 164 cases of Kashgar epidemic in Xinjiang asymptomatic?

  China News Service, Beijing, October 26th. Question: Why are all 164 cases of the Kashgar epidemic in Xinjiang as asymptomatic?

  China News Agency reporter Li Yanan

  There are 1 case, 137 cases, and 26 cases. A total of 164 people have been infected with the new coronavirus in Kashgar, Xinjiang for 3 consecutive days, and all of them are asymptomatic.

  Following the report of a case of asymptomatic infection of new coronary pneumonia in Shufu County, Kashgar Prefecture, Xinjiang on the 24th, local close contacts and close contacts of close contacts were tested for nucleic acid, and 137 asymptomatic infections were found the next day.

Through the free nucleic acid test for all employees immediately carried out in Kashgar, the official report indicated that as of 16:00 on the 26th, there were no confirmed cases of new coronary pneumonia in Xinjiang and 26 new cases of asymptomatic infection, all in Shufu County.

  When analyzing the epidemic, Wang Guangfa, director of the Department of Respiratory and Critical Care Medicine at Peking University First Hospital, pointed out that people infected with the new crown virus can usually be tested for nucleic acid positive 2 days before they develop symptoms. Because most of these patients are in the early stage of the disease, and secondly, because the local response is relatively rapid, they may have been tracked before the symptoms appear.

  "If the infected persons in Kashgar are detected earlier, they may be asymptomatic, but it does not mean that these infected persons will not develop symptoms and turn into confirmed cases in the future," said Chen Xi, an associate professor at the Yale School of Public Health. On the other hand, consider When the infection occurs in the factory, and the workers are mainly young people, the probability of asymptomatic is higher. This situation has appeared in clinics in many parts of the world.

  People who are asymptomatically infected with the new coronavirus are often referred to as "silent communicators" and are now a topic of international concern.

  Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, recently pointed out that the estimated proportion of asymptomatic infections in the United States is 40% to 45%.

  A large-scale population study in 19 countries and regions previously published by the international medical journal "Public Science Library Medicine" showed that asymptomatic infections account for about 20% of the population infected with the new coronavirus.

  Asymptomatic infections have caused statistical problems for all countries due to their own "occult".

Many countries have adjusted the detection and statistics methods of asymptomatic infections several times.

  The first case of asymptomatic infection in this epidemic in Kashgar, Xinjiang, was discovered by local authorities during regular nucleic acid tests conducted by the “should check and do all” personnel in Shufu County, Kashgar.

Further CT examination of this case by the hospital showed no abnormalities, and IgM and IgG antibody tests were all negative.

  At present, although there have been no reports of asymptomatic infections converted to confirmed cases in this epidemic, the source of the epidemic is still unclear, and the transmission chain is still complicated.

  In order to clarify the path of infection, Chen Xi said that antibody testing should be increased in a targeted manner.

"For small areas where a certain amount of infection is suspected, such as Kashgar, where community transmission is not known when it will begin, it is appropriate to add a representative antibody test."

  "According to past experience, if there is no source of asymptomatic cases, you must be very careful." Wang Guangfa said that the range of human activities is limited, and a new crown patient can infect an average of 3 people.

According to this data, the number of asymptomatic infections this time may mean that there have been second, third or even more infectious cases, and the emergence of "super spreaders" cannot be ruled out.

  "We can only call the first case discovered this time the indicated case, and it may not be the first infected case." According to Zeng Guang, the former chief epidemiologist of the Chinese Center for Disease Control and Prevention, the case in Xinjiang this time is The possibility of occurrence in Shufu County is unlikely, and the infection may have been caused by some contact with the outside world.

  Zeng Guang emphasized that at the moment, the urgent task is to put all the asymptomatic infections that have been found on the same level for analysis, concentrate on doing an epidemiological investigation of everyone, and clarify the relationship between the cases.

  Kashgar in Xinjiang is located on the western edge of China and is also an important gateway for China to open up to the west.

As of 16:00 on the 26th, a total of 4,471,700 people had been sampled in the Kashgar area, and the results had been 2,133,600. The official stated that it would ensure that all employees in the Kashgar area complete the nucleic acid test on the 27th.

  "This epidemic is different from the past, because it occurred in rural areas and ethnic minorities, but the detection of the epidemic is still relatively early." In Zeng Guang's view, the scale of the epidemic in Kashgar cannot be determined for the time being. The most important task is to expand nucleic acid testing and concentrate efforts on epidemiological investigations.

  In addition to the possibility that the infected are still in the early stages of infection, will the discovery of a large number of asymptomatic infections mean that the pathogenicity of the virus is weakening?

  "Some of the new coronaviruses found in Asia have been different from the strains found in North America and South America. From a virological point of view, the virus is always adapting to the human body." Chen Xi believes that the new coronavirus is dependent on the human body for a large number of transmissions, and its toxicity There is a possibility that it will gradually decline and become more and more difficult to be discovered.

  In this regard, Zeng Guang analyzed that to determine whether the virus has changed, it is also necessary to conduct genetic analysis of the virus and respect the results of actual investigation and analysis.

"The virulence and transmission of the virus have shown a diversified trend." Zeng Guang said that at present, people have only been dealing with the new coronavirus for ten months. The current view of the virus may be different from the early view of the virus, but it still needs further research.