Chinanews Client Beijing, March 30th (Lang Lang) On March 28th, a new local case from Henan brought the topic of "asymptomatic infection" to the focus of public opinion again. Recently, such cases have been exposed in many places across the country, causing netizens to worry that the "dark arrows are difficult to prevent" in epidemic prevention and control.

Why are n’t asymptomatic infections a confirmed case? Are they contagious? How to prevent "invisible danger"? The epidemic situation is not over yet. The question of "asymptomatic infection" has to be solved!

Screenshot of Henan Provincial Health and Health Commission bulletin

"Dark arrows are difficult to prevent"! Asymptomatic infection

Recently, many regions have reported related cases of asymptomatic infection.

On March 29, the Henan Provincial Health and Health Commission notified a new local case. The patient was Wang Moumou of Luohe City, and a confirmed case of new coronary pneumonia was confirmed at 20:20 on March 28. He had a history of contact with asymptomatic infection.

According to the investigation, Wang Moumou took a long-distance bus at Luohe Bus Station at approximately 10:00 on March 21 to the East Bus Station of Shexian County, Pingdingshan City, accompanied by his classmate Zhang Moumou (Doctor of Shexian People's Hospital) I went down to the countryside to scan the grave, and ate with Zhang Moumou 3 times during the period of Yi County.

On the evening of March 13, Zhang Moumou ate at the restaurant with Liu Moumou, Zhou Moumou (the two were also doctors of the People's Hospital of She County). Liu Moumou had a travel history in Wuhan, and after his return to quarantine, he quarantined for 14 days and expired.

On March 25, Shexian People's Hospital conducted a physical examination of frontline medical staff involved in the prevention and control of the epidemic. During the nucleic acid screening, Zhang Moumou and Zhou Moumou were found to be asymptomatic infection. Liu Moumou nucleic acid test was single positive, Asymptomatic, 3 people are undergoing centralized isolation medical observation.

Coincidentally, Jingmen, Hubei also reported a case of asymptomatic infection on the 29th and announced its activity track. According to the information released by Jingmen, on March 27, 2020, a patient with thyroid disease went to a city hospital (South Campus) for treatment and was admitted to hospital. On March 28, a nucleic acid test was performed, and the result was a positive test for new coronary pneumonia, and the diagnosis was asymptomatic. Infected.

In addition, asymptomatic infections have been reported in recent imported cases abroad.

Now that the epidemic situation is gradually being controlled, the frequent appearance of asymptomatic infections has added new uncertain factors to the prevention and control work.

Data map: On March 13, medical staff of Balingqiao Community Health Service Center in Xinghualing District, Taiyuan City, Shanxi Province collected samples from returnees for nucleic acid testing in the laboratory. Photo by China News Agency reporter Wei Liang

Invisible danger? How to define "asymptomatic infection"

The so-called "asymptomatic infection", according to the "New Coronavirus Pneumonia Prevention and Control Program (Sixth Edition)" issued by the National Health and Health Commission, refers to asthma coronavirus pathogens or serum-specific IgM antibodies without clinical symptoms and respiratory tract specimens Test positive.

In simple terms, it means that the infected person has no clinical symptoms such as fever, cough, and sore throat, but the respiratory tract and other specimens are positive for New Coronavirus. Patients carry the virus, but they do not develop the disease, and they do not even know that they are sick, but they can inadvertently spread the virus to others.

According to Liu Youning, the former director of the Institute of Respiratory Diseases of the People's Liberation Army, those who have been confirmed to be "infected" but asymptomatic can be divided into two types. One is still in the incubation period, and the symptoms will occur after the incubation period. The end result is asymptomatic.

Zeng Yixin, deputy director of the National Health and Health Commission, introduced the path to discovering asymptomatic infections at a press conference on February 14. There are four main sources:

First, close contacts of new coronary pneumonia cases, some of whom were found during the medical observation period;

Secondly, in the investigation of the aggregated epidemic situation, in the process of carrying out some active tests, asymptomatic infection may be found;

Third, during the follow-up of the source of infection of new coronary pneumonia cases, asymptomatic infection may be found during active detection of exposed people;

The fourth is that when people with new coronary pneumonia cases, travel history and residence history in areas of continuous transmission are actively tested, asymptomatic infection may be found.

Zeng Yixin mentioned that experts have judged that according to the general transmission law of infectious diseases and current data, asymptomatic infection is positive for nucleic acid detection, and it is possible to excrete pathogens. The probability is small.

At the outbreak prevention and control conference in Hubei Province on March 27, Liu Jiafa, secretary of the Party Committee of the Hubei Centers for Disease Control and Prevention, mentioned that asymptomatic infection may also become a source of infection, with a certain risk of transmission. However, according to the available data, asymptomatic infection may not be the main source of transmission, and asymptomatic infection should be managed in isolation, and the public need not worry too much.

Data map: On March 13, medical staff at the Balingqiao Community Health Service Center in Xinghualing District, Taiyuan City, Shanxi Province, viewed the throat swab samples taken by returning workers. Photo by China News Agency reporter Wei Liang

Why are asymptomatic infections not yet a confirmed case?

Now that the virus nucleic acid test is positive, is the asymptomatic case a confirmed case?

In the "Monitoring of pneumonia cases of new coronavirus infection (third edition)" released on January 28, "asymptomatic infection" was distinguished from suspected cases, confirmed cases, and mild cases. The test was positive but asymptomatic and was not included in confirmed cases published daily.

On March 7, the "New Coronavirus Pneumonia Prevention and Control Plan (Sixth Edition)" made clear that suspected and confirmed cases should have clinical manifestations. Asymptomatic infection patients have no clinical manifestations, and need to be isolated for 14 days and further testing is needed to make a judgment. If an asymptomatic person develops symptoms during quarantine, they are reported as a confirmed case and published.

That is, according to existing standards, asymptomatic infection is not a confirmed case.

Experts have explained this. An epidemiologist and a member of the high-level expert group of the National Health and Medical Commission previously stated that the test may have a "false positive" result, so further diagnosis and identification of asymptomatic infection is needed, and it cannot be judged as a confirmed case based on a positive test only. .

"Our diagnostic technology is a nucleic acid diagnostic technology, and it cannot be confirmed that it is a live virus. For an asymptomatic test, I don't think it (positive result) can determine whether it is caused by a live virus, a dead virus, or a fragment of a virus. In this case This kind of person needs further identification. "

According to Zeng Guang, the diagnosis of a disease cannot be based on only one test, but also combined with other manifestations to make a comprehensive judgment. Asymptomatic infections should not be considered as patients with new coronary pneumonia, but they may also be in the incubation period, and symptoms may appear at a later stage and be converted to confirmed patients, so they need to be isolated.

Data map: On March 13th, medical staff of Balingqiao Community Health Service Center in Xinghualing District, Taiyuan City, Shanxi Province walked into the company to perform nucleic acid detection and sampling for migrant workers returning to work. Photographed by reporter Wei Liang of China News Agency.

Prevent loopholes! Invisible "infected" need to be vigilant

"We must attach great importance to the prevention and treatment of asymptomatic infections." Premier Li Keqiang of the State Council stressed on March 26 when he hosted a meeting of the Central Leading Group on New Coronary Pneumonia Epidemic Situation.

According to a report from the Chinese Government Network, Li Keqiang mentioned at this meeting, "Are there asymptomatic infections infectious? Will the condition develop and change further? The health and health committee will organize experts to seriously study and judge and come up with scientific prevention and treatment programs. This is an important part of our efforts to consolidate the results of epidemic prevention and control and prevent loopholes in prevention and control. "

Li Keqiang also said that since the outbreak of the new crown pneumonia epidemic, the relevant departments have been continuously adjusting the diagnosis and treatment plan according to changes in the situation, and the situation of asymptomatic infection should also respond to the changes and scientifically respond.

Regarding whether the public is worried that asymptomatic infection will cause a recurrence of the epidemic, Zhong Nanshan, an academician of the Chinese Academy of Engineering, told the media on the 29th that the situation of "asymptomatic infection" in China is currently very limited: there is no specific number, and Not exhaustive. But based on known facts, some inferences can also be made. For example: Generally speaking, the infection rate of asymptomatic infected persons is very high for those who are in close contact with them, but the number of newly diagnosed cases of new coronary pneumonia in China has not risen but has been declining, which can indicate that China has not yet had a large number of " Asymptomatic infection. "

Jiang Rongmeng, a member of the National Health and Medical Commission's expert team for the treatment of the new crown pneumonia epidemic and the chief physician of the infection center of Beijing Ditan Hospital, also said in an interview that after this period of prevention and control across the country, many cases of infection after the infection were diagnosed, closely connected, and related Personnel are treated in isolation, which is the best way to treat asymptomatic people.

"It's just that there may be net leakage for asymptomatic infections with a very long incubation period, but this number is very small, and the chance of further transmission is very small. And once it occurs, it can be found in the existing strict prevention and control screening system. It was found that timely isolation and management of close-connected people will not cause a large-scale outbreak. "Jiang Rongmeng said. (Finish)