On the afternoon of March 31, the National Health and Reform Commission announced for the first time the condition sataout of asymptomatic infections. As of 24hours on March 30, 2020, there were 1541 cases, of which 205 were imported from abroad. At the same time, from April 1st, china will be asymptomatic infection sin listed in the daily notification. Asymptomatic infection refers to the absence of fever, cough, sore throat and other self-perceived clinical symptoms, but also no clinically identifiable symptoms and signs, but respiratory tract and other specimens of new coronavirus pathogen test positive.
Author . . . Gan Xiao Ren Fangyan
On March 30, Li Keqiang chaired a meeting of the central leadership group to deal with the outbreak of new coronary pneumonia, calling for a good effort to consolidate the effectiveness of prevention and control, highlighting the prevention and control of asymptomatic infections.
Who is asymptomatic? How many more of these hidden infected people are there? Will it trigger a second wave of outbreaks? Benjamin Cowling, a professor at the Li Ka-shing School of Medicine at the University of Hong Kong, told China Science Daily: “Whether the second wave of outbreaks will come depends on the end of April, but asymptomatic infections are not the main cause.” “
Who is asymptomatic infection?
On March 31, the State Council Information Office released the latest definition of asymptomatic infection.
In contrast to the definition sympathising with the National Health and Reform Commission’s March 7 “New Coronary Virus Pneumonia Prevention and Control Program (Sixth Edition),” the new definition adds limits on subjective feelings such as “self-perception” and “identifiable symptoms”.
In fact, since the outbreak of the new crown, with asymptomatic infections in various places have been informed, the scientific and technological community has paid great attention to this, and around how to define the discussion.
On January 29, an asymptomatic infection was first detected in Hangzhou, Zhejiang Province.
Wen Yumei, a member of the Chinese Academy of Engineering, emphasized the definition of asymptomatic infections in an interview at the time: “No fever does not mean no symptoms, or mild symptoms are easy to be ignored.” “
“Be very careful not to panic because of miscalculation. “
Lushan, a professor at the University of Massachusetts School of Medicine, also noted that confirming that infected people are indeed asymptomatic and need to rule out false positives for testing methods, cross-contamination in sample stake and testing, and repeatability of data.
On March 29, Jiang Rongmao, a member of the national health and health committee’s expert group and a physician in the second-in-charge of infection at Beijing Ditan Hospital, published an article on his personal WeChat public number “Beijing also cloud infection” that even if the reported “asymptomatic infection” may be caused by mild or unable to properly complain (such as the elderly, children, etc.) or because of the interference of basic diseases such as cardiovascular disease, chronic lung disease and other symptoms lead to information collection, but also there is some objective evidence that “no symptoms” In fact, there are chest X-rays to check for abnormal performance. 
In an interview with Caijing on March 31st, Zhang Qi, vice dean of the UCLA School of Public Health, stressed the importance of eliminating subjective factors: patients may report symptoms such as stomach pain and diarrhea, which may be early symptoms of new coronavirus infection. 
Earlier, a paper published in the New England Journal of Medicine had been published as “Ulong”. Researchers report the first discovery of the new coronavirus in Germany, where the patient was an asymptomatic infection from Shanghai.
A few days later, the researchers wrote to the magazine to clarify the fact that the author had not actually communicated with the woman before publishing the paper, and that the information came only from the four patients in Germany, “who appeared to have no symptoms.”
The patient actually developed symptoms, she felt weak, muscle aches, and took the anti-fever drug paracetamol. 
The new qualifications revolve around the patient’s subjective feelings, responding to previous scientists’ concerns and making research and prevention of asymptomatic infections more accurate and targeted.
“Tip of the Iceberg” will cause a second wave of outbreaks
On February 5, the National Health and Reform Commission released the “New Coronary Virus Infection Pneumonia Treatment Program (Trial 5th Edition)”, the first time that “asymptomatic infections may also become a source of infection.”
Jiang Rongmao in the public article introduced: “From the law of infectious diseases, infectious disease epidemic usually has two ‘iceberg’ phenomenon, that is, the first iceberg phenomenon is the incidence of a few people after infection, which is why to carry out infectious disease reporting, epidemiological investigation, close contact tracking the main reason.” The second iceberg is the minority of severe illness in people who develop the disease after infection. “
At a time when provinces across the country have blown the number of re-work re-production horns, people are worried that “asymptomatic infected people” will not be the third “iceberg” – asymptomatic infected people will not account for a significant proportion of the population? They move freely with the virus, acting like a hidden virus carrier, eventually leading to a second wave of outbreaks.
A number of scientific studies have focused on this issue. For example, researchers such as Gerardo Chowell, an epidemiologist at Georgia State University in the United States, published their study in Eurosurvese in March.
Asymptomatic patients were 17.9 per cent, according to a model statistics for diamond princess patients. In this regard, Jiang Rongmao pointed out in the aforementioned public article, “Diamond Princess” is only a special case.
According to a large sample analysis of more than 70,000 people in the Journal of Chinese Epidemiology on February 17, 889 asymptomatic infections accounted for 1.2% of the total. 
Zhong Nanshan, a member of the Chinese Academy of Engineering, was interviewed, by retweeting the results, to deny the “tip of the iceberg” of asymptomatic infections.
He said that asymptomatic infection stoyushengs are highly transmitted to close contacts, while the number of new confirmed cases in China has not risen or decreased recently, so it can be inferred that China does not have a large number of asymptomatic infections.
“There have been symptomatic infections in all outbreaks and epidemics, but this is not the trigger for a renewed outbreak. “CoVID-19 first appeared in Wuhan in early December 2019, and it wasn’t really confirmed until about a month later,” Goben told China Science Daily. In other countries, the imported infection will take place in the area from late January 2020 to the confirmed community infection in late February, which is also about one month. Thus, failure to strictly control imported cases outside the country and to maintain community isolation is the key to a secondary outbreak. “
Mr Gobben speculated that the effects of the current measures would be revealed around the end of April.
Jin Yongtang, a professor in the Department of Public Health at Zhejiang University School of Medicine, told China Science Daily: “There is no evidence that there is a secondary outbreak in China and asymptomatic infections will lead to the outbreak, otherwise China’s current outbreak and pandemic will not be successfully controlled as scheduled.” “
Incomplete statistics on “asymptomatic infections”
In early January, Shenzhen, Guangdong
On January 24, Professor Yuan Guoyong, a professor at the Faculty of Medicine of the University of Hong Kong, and other scholars published a study in The Lancet reporting that a 10-year-old boy admitted by the team in early January was asymptomaticly infected.
This is a family of five, including a sister-in-law, grandfather, daughter, son-in-law and a 10-year-old boy. After they returned to Shenzhen from Wuhan, four adults developed symptoms. At the insistence of his parents, the 10-year-old boy underwent a CT examination of his lungs and found a glass-stained lesions. 
January 27, Anyang, Henan Province
On January 26, Anyang, Henan Province, announced that five of the new cases were related to each other, none of whom had a history of travel and residence in Wuhan, and three of whom had a history of contact with the woman who had returned from living in Wuhan. The three were the woman’s father and two aunts, and the woman was asymptomatic at the time of the official notification (27 January). 
January 29, Hangzhou, Zhejiang
The first asymptomatic patient in Hangzhou was male, 35 years old, now living in Lin’an District, January 21 from Wuhan to Hangzhou, the investigation did not have fever, cough, diarrhea, vomiting and other clinical symptoms. 
March 16, Guiyang, Guizhou
To a (male, 20 years old, student) for overseas return to Guiyang personnel, from London via Hong Kong to Chengdu after the high-speed rail, on March 15 at 23:43 arrived at Guiyang North Station. It has no fever, no respiratory symptoms, normal blood routine, chest CT for antiquated lesions and nucleic acid test positive, by the provincial expert group confirmed as asymptomatic infection. 
March 28, Henan Weihe
Wang, a patient in Luhe City, was diagnosed after contact with asymptomatic infections. With close contact with Zhang is a doctor at Pingdingshan City,YinXian People’s Hospital, on the evening of March 13 with the same two colleagues Liu and Zhou, and others at the same table in the hotel, and Liu had a history of travel in Wuhan, returned to Yixian County after 14 days of self-isolation.