What is Coronavirus and how Does it Behave

Infectious disease and virus experts say the scale of the current epidemic now points to “self-sustaining” transmission from person to person. They estimated that each infected person reinfected an average of 2 to 3 people.

Testing of the New China virus involves the use of real-time polymerase chain reaction (RT-PCR), which can identify viral RNA in samples. These may swallow swabs, cough samples or blood samples from seriously ill patients.

Here are some of the main characteristics of the new coronavirus found in Wuhan, a city in central China in December, which are causing disease outbreaks in China and elsewhere.

Coronaviruses are a class of viruses that look like their names under a microscope. They are spherical and covered with “crown” -like spikes.

Coronavirus infections have multiple symptoms, including fever, cough, shortness of breath, and difficulty breathing. Mild cases can cause cold symptoms, severe cases can cause pneumonia, severe acute respiratory syndrome (SARS), kidney failure and death.

Like other coronaviruses, newly discovered Chinese coronaviruses can be transmitted from person to person through droplets when the infected person breathes, coughs or sneezes.

The incubation period for a newly discovered virus infection is 1 to 14 days, and there are few signs that it may have spread before symptoms appear.

Expert group of Chinese Academy of Medical Sciences answers new questions about pneumococcal infection

At present, the new coronavirus epidemic is entering a more complex period. On January 27, the Chinese Academy of Medical Sciences specially organized Jin Qi, the director of the Institute of Pathogen Biology of the Chinese Academy of Medical Sciences, and the Department of Epidemiology and Health Statistics of the Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences Guang Liang, Cao Bin, Executive Deputy Dean of the Institute of Respiratory Diseases, Chinese Academy of Medical Sciences, Deputy Dean of China-Japan Hospital, Executive Deputy Director of Respiratory Center, Zhan Qingyuan, Deputy Director of Respiratory Center of Chinese Academy of Medical Sciences, and Deputy Director of Respiratory Center of China-Japan Hospital, etc. Experts to answer questions of public concern.

Q: What is the difference between coronavirus and new coronavirus?

Jin Qi: Coronavirus is a large class of viruses widely existing in nature. In technical terms, it belongs to the genus Trotaviridae, coronaviridae, and coronavirus. It is a class of single-stranded positive chain with a capsule and a genome. RNA viruses can be divided into four genera: α, β, γ and δ. Before the pneumonia epidemic of new coronavirus infection, a total of 6 coronaviruses that could infect humans were found. After being infected with these viruses, people will show different clinical symptoms from common cold to severe lung infections, such as the Middle East breath we are familiar with Syndrome (MERS) and Severe Acute Respiratory Syndrome (SARS). As long as it is a severe respiratory infection, it can be called SARI. The full name of SARI is “severe acute respiratory infection”, and the Chinese translation is “severe acute respiratory infection”.

Now, the “identity” of the new coronavirus that caused the epidemic has been confirmed. Its Chinese name is the new coronavirus Wuhan strain 01, which is classified as 2019-nCoV, and belongs to the coronavirus β genus. The virus was isolated on January 6, 2020. The reason why it is called “new” coronavirus is that the new coronavirus 2019-nCoV discovered in Wuhan this time is a new branch that has not been found in humans before, and is different from SARS and MERS. The successful confirmation of the “identity” of the virus laid an important foundation for the prevention and control of the epidemic.

According to the previous research on the physical and chemical properties of coronaviruses such as SARS and MERS, coronaviruses, including new coronaviruses, are sensitive to heat, 30 minutes at 56 ° C, ether, 75% ethanol (alcohol), chlorine-containing disinfectant, peracetic acid And lipid solvents such as chloroform can effectively inactivate the virus. But it needs to be emphasized that chlorhexidine (chlorhexidine) cannot effectively inactivate the virus.

Q: It is said that pneumonia infected by the new coronavirus is milder than SARS. Is it true?

Shan Guangliang: At present, new coronavirus infection is in the epidemic period. People are still gradually discovering and continuously understanding the source, infectivity, transmission route and diagnosis and treatment of new coronavirus. Based on the currently observed surface phenomena, the new coronavirus 2019-nCoV is simply compared with SARS in terms of lethal harm, infectivity, and speed of transmission. It also lacks clinically systematic and comparable data support and sufficient epidemiology. evidence. At present, China is at a critical juncture in the prevention and control of new-type coronavirus infections. The statement about “new-type coronaviruses being milder than SARS viruses” may be misleading and even weaken the public’s emphasis on prevention. What is more frightening is that Cause some people to have a sense of laxity and fluke.

The latest study of 41 cases of 2019-nCoV infection in Wuhan published by Chinese scholars in The Lancet showed that 2019-nCoV infection has clinical symptoms similar to SARS in respiratory diseases, and the mortality rate should not be underestimated. Therefore, the seriousness of the current epidemic must be taken seriously.

Q: Does the new coronavirus really come from bats? Is there an “intermediate host” during the infection?

Wu Jinqi: More and more scientific evidence suggests that the new coronavirus originated from bats. But the key problem is that bat virus cannot directly infect humans under normal conditions, and may infect humans through “intermediate hosts”. The question now is, who is the “intermediate host”? There are scientific research papers and popular sayings in the society that pointing “suspects” to snakes, tadpoles and other animals require further confirmation. In fact, the determination of the “intermediate host” requires rigorous and recognized scientific procedures, and conclusions cannot be easily reached. It should be encouraged to continue the research of new coronavirus through various scientific methods.

Q: Has the number of confirmed and suspected cases increased so fast across the country, have there been “super communicators”?

Wu Jinqi: The so-called “super communicator” is an epidemiological term that generally refers to a person who is highly infectious and is more likely to infect other people than other patients, which affects the speed and scale of the epidemic. At present, no “super communicators” have been identified in the outbreak.

What I need to understand is that the generation of “super communicators” is affected by many factors. First, according to the law of biological evolution, that is, adaptive changes to the environment conducive to the survival of species. Viral reproduction depends strictly on the place provided by human cells and the required substances, so the ultimate goal of virus evolution must be to enhance infectivity and reduce pathogenicity. Of course, it does not rule out that the phenomenon of enhanced virus pathogenicity occurs within a certain period of time, otherwise the cells All killed by the virus, the virus itself has lost its basis for survival. When the virus mutates in the human body and increases infectivity, the infected person is a “super communicator.” And the phenomenon of one person infecting multiple people is not only due to the emergence of “super communicators”. Infected individuals produce large amounts of virus (critically ill patients, etc.), more viruses are released through coughing, etc., and they have more contact with others in an easily spreadable manner (face-to-face communication, etc.), and infected individuals have multiple Infecting people in a relatively closed environment, etc., will cause one person to cause multiple infections.

Q: What are the ways in which the new coronavirus spreads from person to person?

Cao Bin: From the current situation, more than 95% of pneumonia cases of new coronavirus infection are related to Wuhan. For example, they have been to Wuhan or come from Wuhan. Judging from the incidence of some clustered cases and the infection of medical staff, the characteristics of human-to-human transmission are obvious, and there is a certain range of community transmission. Chinese researchers analyzed a family with a clustered case in Shenzhen. The results showed that the virus sequences isolated from the bodies of several patients were almost the same, suggesting the same source, confirming that the new coronavirus can be transmitted from person to person.

Generally, there are three main ways of virus transmission. One is droplet transmission: droplets produced by coughing, sneezing, talking, etc. enter the susceptible mucosal surface; the second is contact transmission: touching the mouth, nose, or eyes of infected persons after contacting something that the infected person has touched, causing the virus to spread The third is airborne: pathogens can be contagious even after long-distance spread. For the new coronavirus, the isolation and protection measures for the above three transmission routes must be done well.

Q: What are the symptoms if you are unfortunately infected with the new coronavirus?

Zhan Qingyuan: Judging from the current situation, usually patients with fever, fatigue, dry cough as the main manifestations, nasal congestion, runny nose and other upper respiratory symptoms are rare. About half of the patients will experience dyspnea after one week, and a small number of patients can quickly develop into acute respiratory distress syndrome, septic shock, difficult to correct metabolic acidosis, and coagulopathy. Some severe and critically ill patients may have moderate to low fever during the course of the disease, or even no obvious fever. In particular, attention should be paid to the fact that some patients have mild symptoms and no fever. Most patients have a good prognosis, and a few patients are critically ill and even die.

According to a study published in The Lancet in January this year, the common symptoms when patients develop symptoms are fever, cough, and myalgia or fatigue. All patients had pneumonia, and chest CT examination revealed abnormalities; complications included acute respiratory distress syndrome, acute heart injury, and secondary infections. It is worth noting that a number of “atypical” cases have been detected at the local hospital in Wuhan. Patients do not come to see a doctor with respiratory symptoms. Some of them have gastrointestinal symptoms such as diarrhea, some are flustered, have headaches, suffer from conjunctivitis, and even have only mild limb or back muscle pain. Such “atypical” patients will be the hidden source of infection and need to be diagnosed and isolated as soon as possible.

Q: How should the general public protect themselves? In particular, how should the vulnerable groups with low immunity and chronic diseases be protected?

Cao Bin: New coronaviruses have been confirmed to be transmitted from person to person, mainly by the respiratory tract. Elderly people with low immunity need to pay attention to protection, and young people who rarely get sick should also take protective measures. It needs to be emphasized that for people with “strong immunity”, pneumonia infected by the new coronavirus also poses a great threat. Judging from the current situation, 72% of infected people are over 40 years old, and 64% of male infected people. 40% of infected people have other diseases, such as diabetes and hypertension. The National Health Commission issued the “Notice on Strengthening the Medical Treatment of Severe Cases of Pneumonia Infected by New Coronavirus Infection”, requiring all places to attach great importance to the medical treatment of severe cases, focusing on the elderly and special populations with basic diseases, and closely monitoring the condition Variety.

Q: With so many types of masks on the market, which one can be used to prevent new coronaviruses?

Cao Bin: Currently there are several types of masks on the market: First, gauze masks. These masks have poor facial adhesion, low anti-virus efficiency, and cannot be used as medical personal protective equipment. The second is the polyurethane fiber mask, which generally has neither the role of droplet isolation nor the effect of blocking smog. Third, there are many types of disposable medical masks, such as disposable medical masks and disposable medical surgical masks, which are used for general protection of medical staff or for isolation of droplets during invasive operations. The public pays attention to the selection of medical masks with filter layers in order to achieve the effect of blocking liquid and particle filtration. It is especially recommended to use disposable medical surgical masks. Fourth, medical protective masks, N95 masks, this type of mask can prevent airborne diameter ≤ 5μm infection factor or close <1m contact with diseases transmitted by droplets, can filter ≥ 95% of non-oily particles. Specific models including N95, KN95, DS2D can be selected. However, it should be noted that the wearing method of medical protective masks is very important. If they are worn incorrectly, the filtering effect will be affected.

Q: Is only N95 masks effective when respiratory viruses spread?

Cao Bin: Taking flu as a common susceptible infectious disease as an example, in March 2019, the Journal of the American Medical Association (JAMA) published an article confirming that among out-patient medical staff, N95 and surgical masks are effective in preventing influenza. No significant difference. Children with the flu who use masks correctly reduce their family members’ chances of being diagnosed with the disease by 80%, and the difference between the types of masks used is negligible. Influenza A virus and new coronavirus are both RNA viruses that can be transmitted by droplets. We can follow the recommendation of the US Centers for Disease Control and Prevention, that is, put on a mask within 6 feet (about 1.83 meters) of the patient, The strap is attached to the nose, mouth and chin. Try not to touch the mask again until you remove it; if you have a respiratory infection, wear a mask before approaching others; if you need to see a doctor, wear a mask to protect others in the waiting room; if the respiratory infection If the disease spreads in the community, or if you have a high risk of complications, consider wearing a mask in a crowded environment. After wearing a mask, throw it away and wash your hands; never reuse a mask. It can be seen that instead of using high-level masks, it is better to choose ordinary medical masks and strictly follow the wearing rules. Do not discard the mask after wearing to prevent recontamination. It should be folded and thrown into a hospital waste bin labeled “Medical Waste” or a closed hazardous waste bin. In addition, remember to wash your hands after folding the mask, because the folding process may also be exposed to contaminants.

 

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