Scan the QR code with wechat < / P > < p > to share with friends and circle of friends_ blank" href=" https://news.163.com/news/search?keyword=%E6%96%B0%E5%86%A0%E7%97%85%E6%AF%92 "> new coronavirus < / a > for keynote report. He introduced that the new coronavirus and the previous coronavirus, such as < a target = "_ blank" href=" https://news.163.com/news/search?keyword=SARS "> SARS < / a > virus and mers virus are different. They spread rapidly and widely. The epidemiological characteristics are similar to that of < a target ="_ blank" href=" https://news.163.com/news/search?keyword=%E6%B5%81%E6%84%9F "> influenza < / a > virus is similar, updating a lot of previous reports on < a target ="_ blank" href=" https://news.163.com/news/search?keyword=%E4%BC%A0%E6%9F%93%E7%97%85 "> understanding of infectious diseases. In his keynote speech entitled "new understanding of new coronavirus: trends and challenges", Xu Jianguo analyzed the epidemiological characteristics of new coronavirus and the situation of asymptomatic patients. < / P > < p > he pointed out that the new coronavirus has updated our understanding of infectious diseases in the past. It is also different from the previous coronavirus and has the epidemiological characteristics of influenza virus. < / P > < p > for example, the new coronavirus spreads widely. SARS virus has been prevalent in 29 countries and regions. According to previous data, there are 220 countries and regions where the new influenza virus is prevalent, which is similar to the influenza virus. In 2009, influenza A was prevalent in 214 countries and regions. In addition, the spread of new coronavirus is very fast. According to the research in the United States, SARS virus, mers virus and new coronavirus are not in the same order of magnitude. In 8 months, there were 8096 cases of SARS and only 203 cases of mers in 12 months. According to the WHO website, as of April 3, 129902402 new crown confirmed cases have been reported worldwide. < / P > < p > why? According to Xu Jianguo's analysis, this is related to the range of cells that can be infected, the speed of virus replication, and the proportion of asymptomatic infections. < / P > < p > from the perspective of Virology, new coronavirus infects more cells than common coronavirus, SARS virus does not infect goblet and rod cells, new coronavirus can infect ciliated cells, goblet and rod cells.

asymptomatic infection has been regarded as COVID-19's "Achilles heel". He said that in infectious diseases, healthy people who do not get sick but are infectious are very common, such as "Typhoid Mary". However, the proportion of asymptomatic infection in new crown is very high, higher than that in mers and SARS. The proportion of asymptomatic new crown infections in different areas ranged from 6.3% to 96%. < / P > < p > in some epidemic situations in China, it is not patients who are found in the early stage, but asymptomatic infected people, such as Kashgar epidemic in Xinjiang. The main scenes for asymptomatic infected persons to spread the virus include gatherings, banquets, buses, elevators and other confined spaces, shopping, meetings, training and so on. He believes that the discovery and control of asymptomatic infection is a very important link in the control of the epidemic. < / P > < p > in addition, early reports in Wuhan found that the spread of the virus had begun before the new crown patients developed symptoms. Some literatures reported that the peak time of viral load in nasopharyngeal swab of patients with new coronas was shorter than that of SARS virus. SARS is like a mountain peak. From the onset of symptoms to the peak of viral load, there is a "Climbing" process. The viral load of nasopharynx swab had reached the peak before the symptoms of new crown patients appeared, so the risk of infection was very high. < / P > < p > some researchers inoculated the virus into cells to observe its replication speed. The peak time of SARS virus was 72-96 hours, that of new coronavirus was 48-72 hours, and that of influenza virus was 24 hours. < / P > < p > the new coronavirus on the surface of nasal mucus and sputum could survive for 36 hours and 48 hours at relative humidity of 40%, 4 ℃ and 21 ℃. In addition, the new coronavirus has a strong ability to survive in the environment, and its stability on cloth, glass and plastic surface is higher than that of influenza virus, and it is still infectious after 72 hours; the survival time on paper towel, wood, clothes, glass, paper money, stainless steel, plastic and mask surface is 3 hours, 2 days, 2 days, 3 days, 3 days and 5 days respectively when the relative humidity is 65% and 22 ℃ Days, 5 days, 7 days or so. < / P > < p > Beijing News reporter Dai Xuan < / P > < p > Editor Li Yukun Bai Shuang < / P > < p > proofread by Wu Xingfa < / P > < p >