At present, the spread of the local epidemic in China has been basically blocked. With the "unblocking" of Wuhan, the emergence of asymptomatic COVID-19 virus infection has attracted much attention. What are asymptomatic people and how contagious are they? How to deal with the risk of transmission of asymptomatic infections after resuming labor and resuming labor? How do relevant departments and local governments manage and control, and how to check? How should the public protect themselves? For these focus issues that are generally concerned by society, Xinhua News Agency interviewed relevant experts to find out.
Focus One: How infectious are asymptomatic people?
Statistics show that 31 provinces (autonomous regions, municipalities directly under the Central Government) and Xinjiang Production and Construction Corps reported on April 11 63 new cases of asymptomatic infections, including 12 cases of asymptomatic infections imported from abroad; 14 cases were confirmed on the same day (overseas Enter 14 cases); 55 cases of medical observation were released on the day (4 cases were imported overseas). 1086 cases of asymptomatic infection are still under medical observation (332 cases imported from abroad).
Wei Sheng, a professor at the School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, said: "The infectivity of asymptomatic infected people depends on different situations. If it is found in Wuhan after being isolated for so many days, the infectiousness is very low. . If it is an asymptomatic infected person who is found in a population returning from a popular area abroad, the infectivity is very high. It is necessary to judge each case separately. "
According to Tong Zhaohui, a member of the expert group of the Central Steering Group and the deputy director of Beijing Chaoyang Hospital, there are two types of asymptomatic infections: one is COVID-19 confirmed patients, but still in the incubation period, there are no symptoms, they need to be screened out and included in the diagnosis Case management; the other type has no symptoms and no image changes. It is a true asymptomatic infected person. They are not patients, only nucleic acid tests are positive.
The National Health and Health Commission organized experts to analyze the conversion of asymptomatic infections reported from January 29 to April 8 into confirmed cases, and found that the proportion of asymptomatic infections converted to confirmed cases in China showed a gradual downward trend. After March 10, the proportion of confirmed cases remained below 11.2%, and in some provinces the proportion was relatively low, below 6%.
Tong Zhaohui said that it is medically judged that asymptomatic patients have a certain degree of infectivity, but the infectivity is generally weaker, and the infectivity is much lower than those with symptoms. "Without symptoms such as sneezing or coughing, virus-containing droplets cannot be discharged in the respiratory tract, and there is relatively little chance of transmission."
Recently, "Nature" published an online paper entitled "Virology Evaluation of Inpatients with New Coronavirus Pneumonia". A study by the team of German scientist Christian Trausen showed that COVID-19 symptoms no longer exist after 8 days of symptoms. Isolation of live virus means that the patient does not have live virus for a long time.
Wei Sheng said that most residents in Wuhan have been quarantined at home for more than 70 days without symptoms, and people with a "green code" are less contagious. "A lot of people have gone out in Wuhan recently, and very few people with asymptomatic infections have been found."
Focus 2: Will the asymptomatic infection cause a rebound in the epidemic?
On April 8th, the 76-day Lehan-Han Pass was closed and reopened. After the “opening” and resumption of labor in Wuhan, the risk of transmission of asymptomatic infections has attracted much attention.
Li Qun, director of the Center for Health Emergency Response of the Chinese Center for Disease Control and Prevention, said that preparations for resuming work and resuming production have been done all the time to cope with the possible spreading risks as the flow of people increases. Once an asymptomatic infected person is found, carry out quarantine observation and detailed epidemiological investigation in a timely manner, and at the same time, strengthen targeted control and monitoring of some key places, key populations, and key areas. "Through these jobs, we hope to find more asymptomatic people and reduce the chance of transmission."
"The existence of asymptomatic infections is the rule of infectious diseases. Measles, flu, SARS, etc. have a certain proportion of asymptomatic infections, and they have not caused a large spread in society." Tong Zhaohui said that SARS and early 2003 Evidence from the COVID-19 epidemiological survey has proved that asymptomatic patients have a certain degree of infectivity, but the infectivity and spread are limited and will not cause large-scale spread of the population. As long as hospitals and disease control agencies fully implement the "four early" requirements for the prevention and treatment of infectious diseases, they can well control the transmission risk of asymptomatic patients.
"Whether an asymptomatic infected person will cause the epidemic to rebound? More importantly, it depends on the attitude and ability of prevention and control. If you don't pay attention, even a small number of asymptomatic infected people may cause disease transmission; if we pay attention Even if there are asymptomatic infected persons, as long as the prevention and control measures are effectively implemented, one is found, one is controlled, and the work of discovery and control is solidly done, there will be no problems. "Li Qun believes that all aspects have been highly valued at present. For the prevention and control of symptomatic infected persons, the monitoring work of professional departments has been continuously strengthened, the prevention and control measures and processes have been continuously optimized, and the screening of key populations has also been continuously carried out. There is no need to worry too much about the outbreak of asymptomatic infected persons.
Focus Three: How to troubleshoot and control people with asymptomatic infection?
According to experts, there are several main sources of asymptomatic infections detected in Wuhan, Hubei: one is from the close contact of the diagnosed patients; the second is from the ordinary patients who came to the hospital for screening; the third is some enterprises Before the resumption of labor and reorganization, the organization was found out; the fourth was the screening of the separated Chinese personnel.
Once an asymptomatic infected person is identified, what measures will be taken to respond?
Li Qun said that medical and health institutions at all levels and all types of asymptomatic infections should report directly to the Internet within two hours. After receiving reports of asymptomatic infections, the CDC at the county / district level must complete the case investigation of asymptomatic infections within 24 hours.
"For asymptomatic infected persons, the same strict measures as the diagnosed cases are adopted. Asymptomatic infected persons are very strict in management, isolation, and medical observation after they are discovered." Li Qun said, "Asymptomatic infected persons should be concentrated After 14 days of medical observation, once the symptoms appear, they will be transferred to the designated hospital for treatment. If the diagnosis can be confirmed, they must be corrected as confirmed cases in time. After two negative nucleic acid tests, the concentrated medical observation is lifted, and two weeks of health follow-up is required. Weeks and the fourth week will go to designated hospitals for re-examination, and close contacts of asymptomatic patients will also have to focus on medical observation for 14 days. "
Focus Four: How should the public view and protect?
In response to some of the panic emotions of asymptomatic infected people, Tong Zhaohui said that close contacts of confirmed cases are the main source of asymptomatic infected people. People who have not been exposed to COVID-19 patients are generally not infected and there is no need to panic. .
Li Qun said: "The public needs to be aware of the risk of infection, but there is no need to worry too much. When it is impossible to distinguish whether there are asymptomatic people around, it is more important to protect yourself."
Experts generally believe that ordinary people without symptoms and suspicious contact history do not need to do nucleic acid screening. Large-scale screening of the general population is neither feasible nor necessary. What the public has to do is to do personal protection, develop good hygiene habits, increase nutrition, rest well, and improve self-immunity.
Standard protection is also very important, "we may still have some subconscious movements, and some bad habits are not noticed, such as touching the surface of the mask with your hands and then rubbing your eyes." Li Qun said that the public must be conscious on the one hand To do personal protection well, on the one hand, you need to know how to regulate protection.
"I hope that after the outbreak, everyone can develop some good hygiene habits, which is not only beneficial to the prevention of the COVID-19 epidemic, but also to the prevention and control of other infectious diseases." Many experts said that mask hygiene, hand washing hygiene, maintaining social distance, etc. Good hygiene habits should be maintained.
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