Although the outbreak of new coronary pneumonia has been gradually brought under control in China, the topic of “asymptomatic infections” has recently raised concerns. Why is China different from WHO’s standard on “is asymptomatic infection a confirmed?” Will it become a “black hole” in China’s epidemic prevention and control, leading to a second pandemic? Global Times reporter on the 24th interviewed industry experts.
60% of infected people are asymptomatic?
About 60 percent of new coronary infections may be asymptomatic or mild, but their ability to spread the virus is not low, making it harder to stop the new coronary outbreak and may even lead to a secondary outbreak, according to a recent report in the British academic journal Nature. Analysis of cases of infection on the Diamond Princess cruise ship docked in Japan supports this claim, with studies showing that asymptomatic or mild cases on board account for about 40 to 50 per cent of all infected people. Michael Mina, an infectious disease immunologist and epidemiologist at the Harvard School of Public Health, was quoted in the journal Nature as saying that asymptomatic infections are not counted in confirmed cases, which is not conducive to modeling the virus and understanding its spread.
The findings quickly raised concerns on social media, with many mentioning that a symptomatic infection was found in Wuhan’s Lukou district on March 20, but was not included in the list of confirmed patients in accordance with Chinese regulations.
Wang Peiyu, vice dean of Peking University’s School of Public Health, told the Global Times on Thursday that the “60 percent” mentioned in nature magazine was a conclusion that patients with mild, basic sensory and completely non-symptoms came together. He reminded that, according to a statistical report published in the Journal of Chinese Epidemiology by the Expert Group on the Prevention and Control of New Coronavirus pneumonia of the Chinese Society of Preventive Medicine, as of 11 February 2020, a total of 72,314 cases had been reported in mainland China, of which 889 (1.2%) had asymptomatic infections. So the proportion of people with no symptoms is not that high.
Why is the criteria for diagnosis not uniform?
The World Health Organization lists asymptomatic infections as confirmed, but China does not include them in the statistics. The inconsistent standards for confirmed patients have left many wondering. At a press conference held on the 24th of the State Council Joint Defense And Control Mechanism, Wu Zunyou, a researcher at the China Center for Disease Control and Prevention, said that the laboratory diagnostic methods can now detect patients with new coronavirus, but there are no clinical symptoms, this is asymptomatic infection. According to the definition of the New Coronary Virus Pneumonia Treatment Program (Trial 7th Edition), suspected and confirmed cases need to have clinical manifestations, asymptomatic infected people without clinical performance, need to be centrally isolated for 14 days and further testing to determine. If symptoms occur during isolation, it is reported as a confirmed case and published.
Wuhan Health and Health Commission 23 informed that a small number of asymptomatic infections may develop into confirmed cases, but the vast majority will heal themselves. Asymptomatic infections can also become a source of infection, with a certain risk of transmission. However, WHO believes that “based on available data, the new coronavirus is mainly transmitted by patients with symptoms” and therefore asymptomatic infections may not be the main source of transmission. According to the New Coronary Virus Pneumonia Prevention and Control Program (Sixth Edition), asymptomatic infected persons should be centrally isolated for 14 days, after the expiration of isolation, in principle, two consecutive specimen nucleic acid test negative (sampling time at least 24 hours) can be released from isolation.
Wang Peiyu said that for people with no symptoms, there is no need for immediate treatment. In addition, China’s current practice is equivalent to treating it as a suspected or latent patient. He said that we divide the infected people into different levels, for this kind of symptomless, but nucleic acid test positive infected people as suspected cases of observation, isolation, in fact, has reached the effect of prevention and control. Because the infected person has no symptoms, there is no need for medical correspondence and hospitalization, for this situation there is nothing to blame. From a medical resource point of view, this is also the right thing to do, we have not counted this part of the hospital patients, because they do not need treatment, but they are isolated to prevent possible further infection.
How to prevent and control asymptomatic infections
Will asymptomatic infections cause the spread of the epidemic? Wu Zunyou thinks “no”. He said that during isolation observation, some people developed into patients, and some did not show symptoms until the end of isolation, but whether or not there were symptoms, asymptomatic infections were found in close contacts we manage, and were managed. In addition, isolation observation is independent, once the symptoms are found immediately transferred to the hospital for diagnostic treatment, so will not cause the spread of social spread. But this risk should always be of high concern.
Wang Peiyu admitted that asymptomatic infections do cause greater difficulties for our prevention. There are concerns that asymptomatic infections are currently found mainly through close contact screening, cluster outbreak investigation and infection source tracking surveys. If the source of infection is unknown, it is difficult for such infections to be detected. Wang Peiyu said that we are now also aware of this problem, so now take the “internal defense rebound, external defense input” approach. Epidemiologically, there may also be a pandemic after a pandemic, as many diseases have long incubation periods and asymptomatic carriers. We don’t know 100 percent about the new coronavirus, but we are aware of the problem and can’t relax everywhere in preventing the outbreak from rebounding.
At present, more and more returnees, which inevitably include asymptomatic infections, how do we need to prevent and control? Wang Peiyu believes that the customs, 14 days of isolation observation and medical institutions to see the three lines of defense are in place. The key is that every line of defense should be implemented in a tangible way. He said that at present, the north to Guangzhou and other places in this area stressed more strictly, if other places can do the same as the north to Guang, it can be said that basically blocked. I’d
By Li Shikun, Special Correspondent of this newspaper Wei Yunfeng
Asymptomatic infected people lead to re-outbreaks? Expert: It will not cause the spread of the epidemic, but should be of high concern