165438+1October 26th is the first anniversary of the naming of COVID-19 mutant Omicron. On this day a year ago, the World Health Organization officially upgraded Omicron to a worrying variant. However, in 2022125 October, 165438+ WHO pointed out in its first anniversary summary that the disease severity caused by this variant was lower than that caused by Delta on average. The article writes that many factors may have played a role. For example, viruses mainly cause infection and replication of the upper respiratory tract. Due to vaccination and infection, the immunity of people all over the world has been steadily improving.
Figure/vision china
On February, 65438+,Sun Chunlan, Vice Premier of People's Republic of China (PRC), held a forum at the National Health Commission to listen to the opinions and suggestions of the frontline representatives of prevention and control work on optimizing and perfecting prevention and control measures. She pointed out that after nearly three years of anti-epidemic, China's medical and health care and disease control system has stood the test, with effective diagnosis and treatment technology and drugs, especially Chinese medicine. The whole vaccination rate of the national vaccine exceeded 90%, and people's health awareness and literacy were significantly improved. In addition, the pathogenicity of Omicron virus is weakening, which creates conditions for further optimization and improvement of prevention and control measures.
In mouse experiments, the pathogenicity of Omicron decreased by 40 times.
During the three-year epidemic, COVID-19 has been evolving, and the prevalent virus strains are very different from the original virus strains. After the outbreak of Omicron, a very significant trend is that the infectivity is obviously enhanced and the pathogenicity is obviously reduced.
Regarding the pathogenicity of Omicron, Liu Shansi, a virologist at Ohio State University in the United States, said in an interview with China Newsweek that the pathogenicity of Omicron is definitely much weaker than that of COVID-19 strain and Delta, whether in mouse research, in vitro cell infection, or in population-level research. According to the latest research results of his team, the ability of the latest varieties of Omicron to fuse with human cells has increased, which means that their infectivity has increased, but there is no indication that their toxicity has increased.
Michelle, director of the State Key Laboratory of Virology of Wuhan University, told China Newsweek that the research team he led found that the ability of Omicron mutant to infect human lung cells was significantly lower than that of the original strain, and its replication efficiency in cells was 10 times lower than that of the original strain.
In the mouse model, their team's latest research found that infection with 25~50 doses of the original strain can kill mice. However, the latest strain of Omicron needs more than 2000 dosage units to cause the death of mice. That is to say, in the mouse model, the pathogenicity of Omicron is at least 40 times lower than that of the original strain during the Wuhan epidemic in early 2020. At the same time, the lung virus content of mice infected with Omicron is at least 100 times lower than that of the original strain.
Take BA.5, which has been popular in the United States for several months, Liu pointed out that it has not caused a sharp increase in hospitalization rate and mortality rate in the United States. In fact, at the meeting of165438+19 October, Tan Desai, Director-General of the World Health Organization, expressed "cautious optimism". At that time, he cited the statistics of the previous week and pointed out that at the beginning of June 1 1, the number of deaths reported in COVID-19 was slightly higher than 9,400, which was nearly 90% lower than the weekly death toll of more than 75,000 in February this year.
On June 18 this year, the weekly report of China Center for Disease Control and Prevention disclosed the data published by Ma Xin, vice president of Huashan Hospital of Fudan University, and Zhang Wenhong, director of infectious diseases department. At the beginning of the year, among the more than 30,000 COVID-19 patients admitted to Shanghai during the Omicron BA.2 epidemic, only 0.065% developed into severe diseases, and no one developed into critical diseases.
Research data show that the most common clinical manifestations of mild patients are cough and expectoration, fatigue and fever, and the median duration of symptoms is 7 days; The average negative time of nucleic acid is 6 days, in which age, complications and initial symptoms will prolong the negative time of nucleic acid, while vaccination with two or more doses of vaccine will shorten the negative time of nucleic acid.
Guangzhou Huangpu Reception Center was the first reception hospital for infected people in this round of epidemic. From 65438+1October 30th to now, nearly 4,000 infected people have been treated, with almost no serious and critical illness. "This is completely different from last year's Delta strain." In an interview with the media on1/professor kloc-0/.301October 30th, the head of Guangzhou Huangpu Fangcang Medical Team said that only two of the Omicron-infected people they treated had changed their lung CT after entering the cabin, but after analyzing their condition, it was found that their symptoms were not caused by Omicron. Less than 50 patients were transferred from the shelter, and their condition was not serious, but they were all old people and children who were assessed by doctors to be at certain risk. According to the current policy in Guangzhou, they are given priority to be transferred to designated hospitals or sub-designated hospitals with better treatment conditions.
165438+1On the afternoon of 29 October, researcher Chang of China Center for Disease Control and Prevention also said at the press conference that international and domestic monitoring data confirmed that Omicron mutants and their evolutionary branches BA. 1, BA.2 and BA.5 series, including BF.7 and BQ.6544, and foreign studies showed that,
Infected with Omicron, the possibility of sequelae is very small.
165438+1October 30, in an interview with the media, said: At present, the academic community has not confirmed the sequelae. The Third Affiliated Hospital of Sun Yat-sen University is one of the main medical forces in COVID-19.
According to Yu, sequela is defined in medicine, and some patients with infectious diseases will be considered as sequela only if some organ functions can not return to normal for a long time after recovery. For those infected with COVID-19, it can be observed in practice that the clinical manifestations of some patients may last for a long time, such as loss of taste and smell, joint pain, memory loss, chest pain, cough and so on. Some scholars call these "long new crowns", but they can't be classified as "sequela of COVID-19".
"The result of previous studies is that according to the self-reported information provided by patients infected with early variants such as α and δ, about 20% of COVID-19 suffered from memory loss and taste loss after infection." In an interview with China Newsweek, Liu Shansi also said that the definition of COVID-19's sequela has always been vague.
In many studies, infected people answer according to their own feelings. For example, they will report memory loss, fatigue and anxiety, but this is subjective. "How serious is the sequelae of COVID-19, how to define it, and whether factors such as vaccination or other viral infections have an impact are all issues that everyone cares about." Liu Shansi said. Just a few weeks ago, he just attended an academic conference. Some scientists from Yale University and other American institutions got together to discuss how to define and study the sequelae of COVID-19.
More and more researches tend to describe the so-called "sequela of COVID-19" as "symptoms of COVID-19", that is, "LongCovid". 202 1 10 months, according to the World Health Organization, is defined as: symptoms appear after 3 months of infection, and the symptoms last for at least 2 months. Symptoms include: fatigue accompanied by physical pain or mood swings; Cognitive problems; Respiratory problems.
From June 65438 to1October 10 this year, according to an article published in Journal of American Medical Association, the patients who developed COVID-19 after COVID-19 infection in 2020 and 20021year were studied. According to the health survey data of about 65,438+200,000 infected people in COVID-19 in 22 countries, about 6.2% of infected people in COVID-19 developed at least one symptom of COVID-19 after three months, and the symptoms eased with time.
After the popularity of Omicron, "it should be said that the possibility of sequelae of COVID-19 is still very small." Michelle said that after vaccination, the toxicity of Omicron is so low that more than 99% of the infected people are asymptomatic or mild, so it is unlikely that there will be sequelae of COVID-19. Liu Shansi also expressed a similar view. He said that the symptoms of patients infected with Omicron are relatively mild, and the probability of sequelae should be relatively small. Of course, since it is "COVID-19", it will take a long time to observe.
On June 18 this year, The Lancet, an international authoritative medical journal, published the first peer-reviewed study on the symptoms of Omicron mutant with new crown. The results showed that the probability of long-term COVID-19 symptoms after Omicron infection was 20% to 50% lower than that of Delta mutant. However, the researchers pointed out that the study did not have enough data to assess the probability of long-term sequelae of COVID-19 in unvaccinated people, nor did it assess the impact on children.
As of165438+1October 28th, more than 10,000 people have been diagnosed with COVID-19 infection in this round of epidemic in Beijing, and the main strain is Omicron BF.7 mutant. Chen Zhihai, director and chief physician of beijing ditan hospital Infectious Diseases Clinical Center, said in an interview with the media recently that a major clinical feature of COVID-19 infection is persistence, and the whole course of the disease will go through asymptomatic, mild symptoms, aggravated symptoms, relieved symptoms until recovery.
Chen Zhihai said that strain BF.7 has a rapid onset and may appear about three days after infection. At the beginning of the disease, patients may have symptoms such as dry throat, sore throat, cough and fever. From the clinical situation, the fever of Omicron in young adults generally does not exceed 3 days. However, some elderly people, especially those aged 70-90 and above, may have more complicated fever and respiratory symptoms. He also pointed out that according to the characteristics of this round of epidemic in Beijing, except for severe patients, generally mild patients can reach the discharge standard in about two weeks.
At the meeting of1October 29th 165438+29, Mi Feng, spokesman of National Health Commission and vice minister of propaganda department, said that since the outbreak, the China municipal government has been conducting prevention, research, summary and adjustment according to the characteristics of virus variation and the actual understanding of clinical treatment. The factors considered include the transmission ability and pathogenicity characteristics of Omicron mutant, the severity and mortality rate, and the changes of international epidemic situation.
Reporter: Peng
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