Prevention Of Asymptomatic Infections As A Source Of Infection Experts Say, "Do Not Rule Out In Isolation Crowd Outside".

Is it possible for asymptomatic infections to spread? On March 24th, at the press conference of the joint defense and joint control mechanism of the State Council, Wu Zunyou, a researcher at the China Center for Disease Control and prevention, said that asymptomatic infections were found in close contacts of confirmed cases, and they were all managed and would not cause social transmission.

Recently, Wuhan, Xingtai, Dezhou, Mianyang, Chengdu and many other places have imported imported asymptomatic infections. It is also known that other countries also have reports of asymptomatic infections.

In March 20th, the international top academic journal "Nature" published a report that 30%-60%'s new crown infection was asymptomatic or mild, but their ability to transmit the virus was not low. These recessive infected persons may trigger a new outbreak. In February 5th, the national health and Health Committee released the new pneumonia diagnosis and treatment plan for new coronavirus infection (trial version fifth) also made it clear that asymptomatic infection may also become a source of infection.

Wang Guiqiang, director of the Department of infectious diseases of No.1 Hospital of Peking University, member of the national medical expert group, said in an interview with the economic news reporters in twenty-first Century that at present, there is no complete statistical data for asymptomatic infections, and the data in some public reports may not be accurate. However, for asymptomatic infected persons, we should not neglect or exclude those who are outside the isolated observation group. Individuals should be well protected, including wearing masks, gathering less, paying attention to hand hygiene, and constantly ventilating at home and cleaning in time.

Asymptomatic infection may also become a source of infection. Gan Jun system

What is the actual proportion of asymptomatic infections?

According to Hungary's new guide, there are many asymptomatic confirmed infections in Hungary. In March 12th, modeling research by Gerardo Chowell, an epidemiologist at Georgia State University, showed that about 18% of the 700 infected people on the diamond princess cruise ship had never had symptoms.

A paper published in the International Journal of Infectious Diseases in March 13th was conducted to investigate 565 Japanese citizens evacuated from Wuhan in early February, and repeated tests and surveillance of their viruses and symptoms. 13 of the evacuees were infected, of whom 4 (31%) had never had symptoms.

At the same time, there were also asymptomatic infections in Xingtai, Sichuan, Mianyang, Shandong and Dezhou in Hebei, all of which were imported from abroad.

As early as the beginning of February, the economic report reporters made an incomplete statistics in twenty-first Century, and at least a dozen cities had asymptomatic infections.

For asymptomatic infections, Wu Zunyou explained that the new crown pneumonia virus could be detected in these people, but it had no clinical symptoms.

Nature reported that 30%-60%'s new crown infection is asymptomatic or mild, and the ability to transmit the virus is not low. These recessive infections may trigger a new outbreak. Coincidentally, Professor Wu Tangchun, Dean of the school of public health, Huazhong University of Science and Technology, has also released relevant research. It said: "according to our most conservative estimate, at least 59% of the infected persons have not been tested and may infect others."

For the contagion of asymptomatic infections, the fifth edition of the February 4th version of the treatment plan began to mention that asymptomatic infections could also become the source of infection. Li Xingwang, chief expert of the center for infectious diseases diagnosis and treatment of Beijing Ditan Hospital, explains that from the point of view of pathogenesis, since it has virus, it may cause transmission. There is a certain correlation between the amount of virus and the severity of the disease. Asymptomatic infections are relatively mild. "That is to say, the amount of virus will be relatively small, so the transmission capacity will be a little weaker than the patients."

But Wang Guiqiang does not fully agree with the above data. He thinks the actual ratio may not be that high. In February 17th, the China National Center for Disease Control and Prevention (CDC) emergency response mechanism for acute coronavirus pneumonia was published in the Chinese Journal of epidemiology. It was mentioned that as of February 11th, China's CDC received 72314 cases of domestic reports, including 889 cases of asymptomatic infections, accounting for about 1.2%.

For the transmission of asymptomatic infections, Wu Zunyou analysis said that through epidemiological investigation, close contacts of confirmed cases were detected, and close contacts were detected and positive nucleic acid was detected. Some of them will gradually become symptomatic and become confirmed patients. Some people do not have symptoms at the end of the observation, regardless of whether they eventually develop symptoms or not. Asymptomatic infections are found in close contacts and are managed.

Asymptomatic infections will not cause transmission and spread. Because China adopts close observation to close contacts. Once symptoms appear, they will be transferred to hospital for treatment without causing social transmission. But the risk of asymptomatic infection should be highly regarded. Wu Zunyou said.

Gradual escalation of epidemic prevention

Although Wu Zunyou said that asymptomatic infections do not cause social transmission, with the increasing number of imported cases and the relocation of migrant workers everywhere, people are worried that asymptomatic infections will become a potential danger.

The new type of coronavirus pneumonia prevention and control program (Sixth Edition) is also clear. At present, asymptomatic infections are mainly detected through close contacts screening, cluster epidemic investigation and infection source tracking investigation. But Wang Guiqiang told the twenty-first Century economic news reporter that the asymptomatic infection did not exclude people who did not observe isolation.

For the treatment of asymptomatic infections, it is found to be isolated, and the network is directly reported within 2 hours. During the isolation period, nucleic acid detection is continued and further observation is made on whether it has symptoms, or some antiviral drugs can be used for intervention. In principle, the nucleic acid test is negative after two successive tests before isolation can be removed.

For the potential risk of infection among asymptomatic infected persons, Wang Guiqiang stressed that individuals should be well protected, including wearing masks, gathering less, paying attention to hand hygiene, and constantly ventilating at home and cleaning in time.

At the same time, whether the asymptomatic infection is included in the confirmed case has become a hot topic again.

Ceng Yixin, deputy director of the national health and Health Committee, said at a news conference in February 14th that according to the relevant regulations of the epidemic, only the suspected cases and confirmed cases of the new crown pneumonia were announced. Asymptomatic infection is not a case and should not be published.

In fact, the requirements for prevention and control of asymptomatic infections have been raised in several editions. The prevention and control plan of the third edition mentioned that if there is a strong epidemic in the locals and when the medical resources are tight, asymptomatic infected persons can take home treatment and observation. To the fourth edition of the prevention and control plan, the asymptomatic infection needs to be segregated for 14 days or after isolation for 7 days. In the February 21st version of the fifth version of the prevention and control plan, it was proposed that on the basis of 14 days of centralized isolation, the nucleic acid test for two consecutive samples could not be isolated until the negative results were detected.

Previously, Heilongjiang province had concentrated on developing nucleic acid screening work papers for close contacts, and carried out nucleic acid laboratory screening for close contacts of confirmed cases, asymptomatic infected persons and suspected cases. At the same time, laboratory nucleic acid screening tests were carried out for close contacts of asymptomatic infected persons.

At present, in order to prevent overseas imported cases, Beijing and Shenzhen require entry personnel to do nucleic acid testing, to better diagnose cases and prevent further transmission, which is also helpful to detect asymptomatic infections.

However, CEO, a gene testing company, told the twenty-first Century economic news reporter that it is recommended that nucleic acid testing be done as well as antibody testing. "Nucleic acid detection is positive only for 30%-50%, and some people need more tests to detect positive. In fact, any virus is detected in a regular hospital with nucleic acids and antibodies, and two kinds of immune tests are simultaneous.

The above CEO said that the national "new coronavirus pneumonia prevention and control program (Seventh Edition)" also explicitly added the antibody detection item, because nucleic acid detection and antibody detection at the same time, the detection accuracy rate is more than 95%. (Editor: Lin Hong)

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