At present, the spread of new local coronavirus in China has been basically stopped, but the asymptomatic infection of new coronavirus has attracted much attention.
What are asymptomatic people and how contagious are they? How should people protect themselves? Xinhua News Agency interviewed relevant experts to answer these focus issues that are generally concerned by the society.
Focus 1: How infectious are asymptomatic people?
Wei Sheng, a professor at the School of Public Health of Tongji Medical College of Huazhong University of Science and Technology, said:
"The infectivity of asymptomatic infected persons depends on different situations. If it is an asymptomatic infected person who has been found in Wuhan after being isolated for so many days, the infectivity is very low.
If it is an asymptomatic infected person found in a population returning from a prevalent area abroad, the infectivity is very high. Different situations should be judged separately. "
According to Tong Zhaohui, deputy director of Beijing Chaoyang Hospital, there are two types of asymptomatic infections: one is a patient diagnosed with a new type of coronavirus pneumonia but is still in the incubation period and has no symptoms. They need to be screened out and included in the management of confirmed cases.
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."
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?
On April 8, the 76-day Lihan Channel was closed and reopened. After resuming work and resuming labor, 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 law 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 the evidence of the SARS and the pre-epidemic survey of the new coronavirus pneumonia in 2003 all proved that asymptomatic patients have certain 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 there is no problem in finding, managing, and controlling.
Li Qun believes that the prevention and control of asymptomatic infected people has been highly valued in all aspects. 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 is also continuing. Don't worry too much Asymptomatic infections can cause outbreaks.
Focus 3: How to troubleshoot and control people with asymptomatic infection?
According to experts, there are several main sources of asymptomatic infections detected in Wuhan, Hubei: First, they were identified from close contacts of diagnosed patients.
The second is to screen out the ordinary patients who came to the hospital for treatment; the third is to screen out the organization of some enterprises before resuming production; the fourth is to screen out 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 confirmed cases are taken. Asymptomatic infected persons are very strict in management, isolation, and medical observation after they find out."
Li Qun said, "People with asymptomatic infections must be concentrated in medical observation for 14 days. Once symptoms appear, they will be transferred to designated hospitals for treatment. If they can be diagnosed, they must be corrected as confirmed cases in a timely manner. Two weeks of health follow-up will be conducted, and the second and fourth weeks will be reviewed at designated hospitals. Close contacts of asymptomatic patients will also be concentrated in medical observation for 14 days. "
Focus 4: How should the public view and protect?
In response to some of the panic emotions of asymptomatic infections, Tong Zhaohui said that close contacts of confirmed cases are the main source of asymptomatic infections. People who have not been exposed to patients with new coronavirus pneumonia are generally not infected and unnecessary. 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 prevent the new coronavirus pneumonia epidemic, but also to prevent and control other infectious diseases."
Many experts said that good hygiene habits such as mask hygiene, hand washing hygiene, and maintaining social distance should be maintained.
Special Report: Fighting The New Coronavirus
