Asymptomatic infections can not be ignored Experts: do not rule out appearing outside the isolated population

Wang Guiqiang, director of the Infectious Diseases Department at Peking University’s First Hospital, told the 21st Century Economic Report that there are no complete statistics on asymptomatic infections, and that some public reports may not be accurate and not as high. However, asymptomatic infections are still not to be ignored, nor do they exclude the presence of groups outside the isolated observation population.

Asymptomatic infections can not be ignored Experts: do not rule out appearing outside the isolated population

Does it cause spread of transmission for asymptomatic infections? On March 24, at the launch of the State Council’s joint defense and control mechanism, Wu Zunyou, a researcher at the China Center for Disease Control and Prevention, said that asymptomatic infections were found in close contacts with confirmed cases and were managed without social transmission.

Recently, Wuhan, Yantai, Texas, Mianyang, Chengdu and many other places have emerged from overseas imported asymptomatic infection cases. It is also known that other countries have also reported asymptomatic infections.

On March 20th Nature, the world’s leading academic journal, published a report that said 30 to 60 percent of new coronary infections were asymptomatic or mild, but their ability to spread the virus was not low, and that these recessive infections could trigger a new outbreak. On February 5th the National Health And Health Council issued the Pneumonia Treatment Programme for New Coronary Virus Infections (Trial 5th Edition), which also makes it clear that asymptomatic infections can also be a source of infection.

Wang Guiqiang, a member of the National Medical Expert Group and director of the Infectious Diseases Department at Peking University’s First Hospital, told the 21st Century Economic Report that there are no complete statistics on asymptomatic infections, and that some public reports may not be accurate and not as high. But for asymptomatic infected people still can not be ignored, also do not rule out appearing in the isolation of the group outside the observation of the population, individuals still want to do a good job of protection, including wearing a good mask, less gathering, pay attention to hand hygiene, home should be often ventilated and timely cleaning and so on.

What is the actual proportion of asymptomatic infections?

Hungary has seen a number of asymptomatic confirmed infections, according to the Hungarian New Guide. On March 12, Georgia State University epidemiologist Gerardo Chowell released a modeling study that showed that about 18 percent of the roughly 700 infected people on board the Diamond Princess had never developed symptoms.

In a paper published March 13 in The Journal of Nature Diseases, the study looked at 565 Japanese citizens evacuated from Wuhan in early February and repeatedly tested and monitored their viruses and symptoms. Of these, 13 evacuees were infected, four of whom (31 per cent) never developed symptoms.

At the same time, Hebei Yantai, Sichuan Mianyang, Shandong And other places also appear asymptomatic infection cases, are imported cases from abroad.

As early as early February, a 21st century economic reporter did an incomplete statistic, at least a dozen cities have asymptomatic infections.

For asymptomatic infections, Wu Zunyou explained that these groups can detect the new coronary pneumonia virus, but without any clinical symptoms.

The Nature report says 30-60 percent of new coronary infections are asymptomatic or mild, and the ability to spread the virus is not low, and these recessive infections can trigger a new outbreak. “According to our most conservative estimate, at least 59% of those infected are untested and may have infected others, ” said Professor Yu Tangchun, dean of the School of Public Health at Huazhong University of Science and Technology. “

For the infectiousness of asymptomatic infections, the fifth edition of the consultation programme issued on 4 February began to mention that asymptomatic infections may also be the source of infection. Li Sheng, chief expert at the Center for Infectious Disease Diagnosis and Research at Beijing Ditan Hospital, explains that since the pathogenesis is concerned, it can cause transmission. The amount of the virus and the severity of the disease has a certain correlation, asymptomatic infected people relatively mild, “that is to say, the amount of the virus will be less, so in the transmission capacity will be a little less proportion of the patient.” “

But for the above data, Wang Guiqiang does not fully agree, he thinks the actual proportion may not be that high. On February 17, the Epidemiology Group of the China Center for Disease Control and Prevention’s Emergency Response Mechanism for New Coronary Virus Pneumonia published a paper in the Journal of Chinese Epidemiology, which mentioned that as of February 11, the CDC had received 72,314 reported cases in China, containing 889 asymptomatic infections, representing about 1.2%.

For the spread of asymptomatic infections, Wu Zunyou analysis, through epidemiological investigation found that the confirmed cases of close contact, close contacts to test, found positive nucleic acid. Some of them will slowly develop symptoms and become confirmed patients, and some people will not show symptoms until the end of observation, regardless of whether or not the symptoms eventually occur, asymptomatic infections are found in close contact, are managed.

“Asymptomatic infections do not cause spread. Because China has taken isolation observation measures against close contacts, it does not cause social transmission if symptoms are referred to hospitals. However, the risk of asymptomatic infection is of great concern. Wu Zunyou said.

Epidemic prevention gradually escalated

Although Wu Zunyou said that asymptomatic infections will not cause social transmission, but with the increase in imported cases from abroad, the flow of new work around, the public fear that asymptomatic infections become potentially “dangerous.”

The New Coronary Virus Pneumonia Prevention and Control Program (Sixth Edition) is also clear, and is currently found to be asymptomatic through close contact screening, cluster outbreak investigation and infection source tracking survey. But Wang Guiqiang told the 21st Century Economic Report that it is not ruled out that asymptomatic infections appear in people who do not observe isolation.

For asymptomatic infections, the treatment is found to be isolated, and within 2 hours of direct online reporting, nucleic acid testing continues during isolation and further observation of symptoms, and some antiviral drugs can also be used to intervene. In principle, two consecutive specimen nucleic acid test sour sat negative before the isolation can be lifted.

And for the potential asymptomatic infection risk, Wang Guiqiang stressed that individuals should do a good job of protection, including wearing a good mask, less gathering, pay attention to hand hygiene, home should be often ventilated and timely cleaning.

At the same time, whether asymptomatic infections are included in the publication of confirmed cases has again become the focus of much debate.

Zeng Yixin, deputy director of the National Health and Health Commission, said at a press conference on February 14 th, in accordance with the relevant regulations issued by the outbreak, only the new coronary pneumonia suspected cases and confirmed cases will be announced. “Asymptomatic infections are not cases and do not need to be made public.”

In fact, the prevention and control requirements for asymptomatic infections have also been increased in several versions of the program. The third version of the prevention and control program mentioned, such as the local occurrence of a strong epidemic, medical resources are tight, asymptomatic infected people can take home treatment and observation. To the fourth version of the prevention and control program mentioned that asymptomatic infected people need to be centrally isolated for 14 days, or after 7 days of isolation nucleic acid test negative can be released from isolation. The fifth version of the prevention and control program updated on February 21st proposed that on the basis of 14 days of centralized isolation, in principle, two consecutive specimen nucleic acid tests were negative before the isolation can be lifted.

Previously, Heilongjiang Province has issued a centralized contact nucleic acid testing work paper, for confirmed cases, asymptomatic infections, suspected cases of close contacts to carry out nucleic acid laboratory testing screening work, screening out of asymptomatic infected persons concentrated in the designated hospital for centralized isolation medical observation. At the same time, close contacts of asymptomatic infections are screened for laboratory nucleic acid testing, cycle-to-cycle, and rolling screening.

At present, in order to prevent overseas imported cases, Beijing, Shenzhen and so on have asked immigrants to do nucleic acid testing, better confirmed cases, to prevent further transmission, which is also conducive to the discovery of asymptomatic infection.

However, a gene testing company CEO told the 21st Century Economic Report that it is recommended to do nucleic acid testing at the same time as antibody testing. “The nucleic acid test is only 30%-50%, and there are some people who need to test to be positive. Any virus is actually tested in a conventional hospital is nucleic acids and antibodies, and immune testing both are on the same. “

The CEO said that the national “new coronavirus pneumonia prevention and control program (7th edition)” also explicitly added antibody testing this one, because nucleic acid testing and antibody testing at the same time, the detection accuracy of more than 95%.