Two months after Omilon appeared in China, China's epidemic prevention strategy decisively chose scientific adjustment.
On March 15, the National Health Commission issued the Diagnosis and Treatment Plan for Novel Coronavirus Pneumonia (Trial Version 9) (hereinafter referred to as the Ninth Edition). This is nearly a year apart from the release of the eighth edition in April 2021. During this period, Delta and Omikerong mutant strains appeared one after another, becoming the main epidemic strains in the world. China has also repeatedly faced the local epidemics of Delta and Olmi kerong, and under the general policy of "dynamic clearance", it has achieved rapid clearance of local outbreaks.
But that changed in 2022, with Ami kerong rapidly spreading to many provinces in China and local outbreaks far exceeding those in the past. This shows that under the non-medical prevention and control measures, in the future, the Epidemic of Omicron will also exist in a situation with a large number of infected people and a wide range of infections. At the same time, although mass vaccination has reduced severity and deaths, the majority of those infected are asymptomatic and mild. However, it cannot be ignored that Omi kerong still has a fatal injurious effect on high-risk groups and people with gaps in immunity.
In the face of the faster spread and more stealthy Omicron, China's epidemic prevention and control has entered the second half, how to play a beautiful epidemic prevention war in the second half, the existing prevention and control strategy is facing a series of challenges, and it is necessary to achieve earlier, faster, stricter and more practical optimization and upgrading.
The mutated virus poses new prevention and control challenges
In the more than 3 months of the global epidemic in Omikerong, the scientific community has gradually seen its face: First, the global vaccine has been reduced to varying degrees in the effectiveness of vaccines to prevent Omiljung infection. For example, in the United States, with a 68.5% vaccination rate for people over the age of 5, the number of confirmed cases has increased by more than 800,000.
Second, closing the country's doors will not prevent The Entry of Aumilon. After South Africa discovered the Aumechjong mutation, Britain and the United States quickly cut off flights, but TheOmilon still quickly entered britain and the United States and became the dominant poison.
At the same time, for fast, stealthy transmission, it is much more difficult to achieve dynamic zeroing. Judging from the local Opichron epidemic caused by Beijing's "international mail" and Zhejiang's "equipment movement", Aomi Kerong does not rely solely on the cold chain as a transmission path. Due to the existence of international trade, it is difficult to import external defenseSmikeron.
Not only is the spread fast, the generation transmission time is short, Omi Kerong will produce more asymptomatic infected people, and some asymptomatic infected people will turn negative in three or five days, and they will not be caught at all. The hidden transmission of Omi kerong adds difficulty to traceability and prevention and control, and the result is often that when an epidemic point is found, the transmission has already reached a large area. An infectious disease expert said that between January and February 23 this year, there were nearly 25 outbreaks across the country, and none of them could find the cause.
"In the future, China may be in a multi-point, sporadic state, and the number of infected people will exceed the past." A high-level epidemiologist believes.
This poses a challenge to the current prevention and control policies of uprooting and clearing the source.
On March 17, the staff of a nucleic acid sampling point in Maidao Square, Laoshan District, Qingdao City, displayed the label, which was obtained by the public who had received the sample. Xinhua News Agency photo.
"Our past prevention and control policies were effective, and it is also because the epidemiological characteristics of the original strain and the Delta variant strain have given us a certain amount of space and time for prevention and control in terms of the time and speed of transmission across generations." An infectious disease expert said.
From the original strain to Delta, the interval between the generations has changed from 4 or 5 days to about 3 days. Studies have shown that the transmission rate of the BA.1 subtype of the Omiljun strain is 77% faster than that of the Delta strain, and the spread rate of BA.2 is 66% faster than that of BA.1.
At present, the Aumechjong mutant strain has become the dominant strain imported from outside the mainland and the local epidemic, and the proportion of the sub-branch of the Aomi Kerong BA.2 has also increased significantly in the past two months, and the spread has been further enhanced. At present, Omiljung has spread to 28 provinces in Chinese mainland, and the number of new infections in the day has surged from 139 on January 9 to 5275 on March 14.
"Therefore, we have to adjust our strategy for the characteristics of the current epidemic, although the choice is very difficult, but it is still necessary." The infectious disease expert said that if the original control and diagnosis and treatment measures are still followed, it is too difficult, and we must strive for a smaller cost and obtain the greatest results.
However, how should the tactics of warfare be adjusted in the future?
One of the new tactics: how to make the community containment strategy more scientific
On the basis of careful study of the transmission characteristics and case characteristics of mutant strains such as Delta and Omiljung, and in-depth analysis of relevant research results, the new version of the diagnosis and treatment plan believes that after infection or vaccination with the new coronavirus, a certain immunity can be obtained, and those who have been vaccinated and infected with Omiljung are mainly asymptomatic and mild.
As of March 14, China's total vaccination rate had reached 87.9%. In such a high proportion of people who have obtained the vaccine immunization base, the infected people are mainly asymptomatic infected and mild cases, Zhang Wenhong, director of the National Infectious Disease Medical Center and head of the Shanghai New Crown Pneumonia Medical Treatment Expert Group, said in an interview with People's Daily that the demand for clinically specific treatment has been significantly reduced, and more as long as symptomatic treatment and disease observation can be given.
"If it is managed according to the past case model, medical institutions will be overwhelmed and will either choose to increase the service capacity of medical institutions or change the rules of case management." This is what the characteristics of the current epidemic determine, and we must change the place. The above infectious disease expert said.
It is based on these new characteristics that the Ninth Edition has made appropriate adjustments, classifying and treating cases, requiring that "mild cases be subject to centralized isolation management, and symptomatic treatment and disease monitoring should be done during the isolation management period, and if the condition worsens, it should be transferred to a designated hospital for treatment." ”
At the same time, the Ninth Edition reduced the nucleic acid detection Ct value of the discharge standard from 40 to 35, reducing the length of hospital stay for cases, and revised "continue to carry out isolation management and health monitoring for 14 days after discharge" to "continue to carry out home health monitoring after lifting isolation management or continuing 7 days after discharge".
A head of a company that produces nucleic acid diagnostic reagents revealed that Ct values are less than 35 before they are managed according to cases, a change that can reduce the number of controlled patients by nearly 30%.
As a result, the pressure on the health care system has been alleviated accordingly, but the community containment system still needs to be changed.
In the prevention and control of the epidemic, a very important part is to determine the close connection and sub-close connection according to the flow investigation, and take different control measures for it.
The above-mentioned person in charge also said that in the current epidemic situation in some places, some of the new cases appear outside the sealing and control area, rather than as in the past, the new cases after the closure are basically the population in the sealing and control area. It can be seen that the sealing and control strategy needs to be judged.
In the past two years, community containment has played an important role in the prevention and control of China's new crown epidemic, and how to better adapt to the characteristics of Omicron is particularly important for further research.
"According to the characteristics of Omikeron, it is possible to seal a community, but sealing a region and a city is obviously not in line with the characteristics of the current epidemic." The above experts said that so many asymptomatic infected people have strong transmission ability, and even pass by, a sneeze, a cough, complete the transmission, do not need to be in close contact in a room.
However, how to carry out more accurate and scientific sealing and control still needs to be adjusted after scientific research.
The second method of new warfare: eliminate the immunity gap
Due to the existence of vaccines, the epidemiological characteristics of Omikron have changed their trajectory.
Data on severe illness and death caused by Aomi Kerong in many countries also show that it is closely related to whether or not to vaccinate.
During the Omiljung epidemic in the United States, the daily number of disease deaths was around 2400. According to a report released by the U.S. Centers for Disease Control and Prevention, unvaccinated people are 13 times more likely to die from the virus than fully vaccinated people and 97 times more likely than those who are boosted by needles.
In the Omiljung outbreak in Hong Kong, China, 91.3% of the 3,444 deaths as of March 11 had not been vaccinated. In all cases, the case fatality rate for completing two doses was 0.04 per cent, and for unvaccinated patients, the case fatality rate was 1.25 per cent, up to 31 times higher. If the elderly over 80 years of age have not been vaccinated, the case fatality rate is as high as 8.6%, and if two doses of the vaccine have been given, the case fatality rate is 1.57%.
Photo credit: Department of Health, Hong Kong.
Although vaccines for all existing technical routes have reduced their protective efficacy against Aomi Kerong infection, they are still able to reduce severe illness and death.
But at present, there is still an immune gap.
"Although China has a high vaccination rate, there is no COVID-19 vaccine in the world among people younger than 3 years old. This would be one of the lowest immune depressions in the world. A public health expert said.
The public health expert said that from the current transmission characteristics of Omikerong, the autoimmunity of people less than 3 years old is not yet perfect, which will also lead to infection in this group. In the Omiljung outbreak in Hong Kong, infants and young children who have died 11 months old need attention.
Unlike previous mutant strains, Omi kerong brought more infections and severe illness and death in children.
The latest data shows that up to 1/3 of confirmed children with COVID-19 in the United States died during the surge in Opmikharong cases. According to the Centers for Disease Control and Prevention, 550 children have died of COVID-19 in the United States since the beginning of this year, compared with 1,017 deaths in the previous 22 months. The effects of Aumechjong on children may be different from previous mutant strains. It tends to affect the upper respiratory tract in children, which is narrower and more susceptible to irritation.
Jason, a pediatric critical care specialist at Commer Children's Hospital at University of Chicago Medical Center, found a massive surge in hospitalized children during the spread of Thermo Chemikoron.
During the Omiljung outbreak in Hong Kong, 17% of the infections were pediatric patients under the age of 17, of which 9% were under the age of 6.
In response to this immunization gap, the above-mentioned public health experts said that they hope that domestic vaccine companies will carry out research on children under 3 years of age as soon as possible, and come up with research data as soon as possible to eliminate the vaccine immunization gap in China.
On March 15, medical workers vaccinated citizens at a vaccination site in Xiamen. Xinhua News Agency photo.
The third method of operation: greatly increase the vaccination rate of the enhanced injection
The ninth edition of the protocol states that "those who have been vaccinated and infected with the Omiljung strain are predominantly asymptomatic and mild." ”
China has implemented COVID-19 vaccination among the whole population, which has played a key role in the prevention and control of the epidemic. However, there are still some areas and populations where the proportion of vaccination needs to be increased. According to data from February 15, 2022, the national COVID-19 vaccination coverage rate was 89.9%, and the full vaccination rate was 87.4%. However, vaccination rates are low for people over 60 years of age, with vaccination rates ≤ 80% in 12 provinces.
Due to the high risk of infection and severe illness in the elderly, areas with low coverage over the age of 60 need to be paid attention to and vaccination rates increased as soon as possible.
Second, the newly emerged Omiljung variant has a very large mutation in the S gene, the main target of the vaccine, resulting in a significant decrease in neutralizing antibody titers and severe immune escape. Although the neutralizing antibody titer can be greatly increased by boosting the needle, the current vaccination of the booster needle is not ideal.
As of February 15, 2022, 40.1% of the population in mainland China who had completed basic immunization had completed strengthening. Booster immunization is currently carried out only among people over 18 years of age, and by age group, the coverage rate of people aged 40-49 and 50-59 years is more than 50%, and the coverage of people over 60 years of age is less than 30%. In addition, the overall coverage of enhanced immunization in some provinces is less than 30%.
At a press conference on the Joint Prevention and Control Mechanism of the State Council on March 15, Wang Huaqing, chief expert of the immunization program of the Chinese Center for Disease Control and Prevention, called for "the harm caused by Aomi Kerong to the elderly is still relatively large." The elderly who have not been vaccinated should be vaccinated as soon as possible, and those who have not been vaccinated should be revaccinated as soon as possible. In addition, after vaccination, according to the regulations, if the population that meets the requirements for intensive vaccination is reached, it is necessary to carry out intensive vaccination as soon as possible at the specified interval. ”
In order to cope with the escalation of the epidemic in Omilon, two doses of vaccination procedures have been completed, in line with the intensive injection population, and more vaccination needs to be promoted. According to the arguments of the vaccine research and development special class, the reinforcement needle can choose homologous enhanced immunization and sequential enhanced vaccination, and both combinations can greatly improve the neutralizing antibody level of the recipient, and also have better safety.
The fourth method of the new war: accelerate the research and development of new crown drugs
For now, it is clear that any one approach alone can no longer set a timeline for the COVID-19 epidemic.
The dynamic clearance of non-medical prevention and control methods and vaccines have confirmed the role of prevention and control, but these two means alone can no longer meet the needs of responding to the Epidemic in Omicron.
"Vaccination can reduce severe illness and death, and dynamic zeroing can reduce the scope of infection, but these cannot prevent the emergence of infection cases, nor can we avoid the symptoms and severe diseases of special populations that need treatment, so we still need drugs, which are three important prevention and control swords in China in the future." One clinician said.
The Ninth Edition also proposes that the State Food and Drug Administration recently approved PF-07321332/ritonavir tablets (Paxlovid) and domestic monoclonal antibodies (amphavir monoclonal antibody/romimab injection) two specific anti-new coronavirus drugs, both included in the list of recommended treatment drugs.
"The adjustment of the drug is also a layout for the Possible More Infected People in the Oprickon epidemic, as well as the non-hospitalization treatment of mild diseases." The clinician said.
The Standing Committee of the Political Bureau of the CPC Central Committee held a meeting on March 17 to analyze the situation of the new crown pneumonia epidemic and deploy strict efforts to prevent and control the epidemic. The meeting stressed that more effective measures should be taken to achieve the greatest prevention and control effect at the lowest cost and minimize the impact of the epidemic on economic and social development. The meeting also stressed that it is necessary to accelerate the reform of the disease control system, expand the monitoring coverage of key populations, improve the level of scientific and accurate prevention and control, continuously optimize epidemic prevention and control measures, and strengthen scientific and technological research such as vaccines, rapid detection reagents and drug research and development, so as to make prevention and control work more targeted.
In the second half of China's fight against the epidemic, it still has to hand over a high-scoring answer sheet.