Author: Wu Simin

  With the rapid spread of new coronavirus variants, high-risk groups such as the elderly continue to face the risk of infection, and it is urgent to further strengthen preventive measures.

At present, the coverage of the first booster dose of the new crown vaccine in my country's elderly population has yet to be expanded, and the vaccination plan for the second booster dose, which focuses on immune vulnerable groups, has been officially launched in many places across the country.

  On the 13th, the Comprehensive Group of the Joint Prevention and Control Mechanism of the State Council issued the "Implementation Plan for the Second Dose of New Coronavirus Vaccine Enhanced Immunization" (hereinafter referred to as the "Implementation Plan"), proposing that at this stage, on the basis of the first dose of enhanced immunization, the The second dose of booster immunization is carried out among people at high risk of infection, people over 60 years old, people with more serious underlying diseases and people with low immunity.

  First Financial Group found that only one week after the release of the implementation plan, as of the 20th, Beijing, Shanghai, Guangzhou, Shenzhen, Changsha, Shijiazhuang, Zhengzhou, Haikou, Chongqing, Zhejiang, Jiangsu, Anhui and other provinces and cities have officially launched. The doses provided by regions and vaccination units vary.

  "Vaccination work has been carried out by the preventive health care department of the hospital. Since the 16th, our community hospital can carry out the second dose of booster injection. But there are several problems in the work: First, the vaccines available in our hospital One of Feilong Koma's recombinant new crown vaccines; the second is that some of the people who came to consult the fourth injection recently are young and middle-aged people or people who have just become "Yangkang", and a considerable proportion of elderly people in the community have not yet started the first dose of booster injection. "The medical staff of a community hospital in Chongqing told China Business News.

  In recent years, the number of people infected with the new crown has increased rapidly in many places. Against this background, will vaccination increase the exposure risk of immune vulnerable groups?

If I get infected at the time of vaccination, can the fourth injection work in time?

After "Yangkang", is it necessary to inoculate the fourth shot in the short term?

How effective is the "fourth stitch" activation?

  Once the "fourth injection" of the new crown for special groups was opened, it was quickly rolled out in many places across the country.

  On the evening of the 19th, the official WeChat account "Shushan Release" of Shushan District, Hefei announced that in order to further improve the response to the new crown pneumonia epidemic, ensure the safety and health of the people, and facilitate the second dose of booster immunization for the general public, The Anhui Provincial Health Commission and the Anhui Provincial Data Resources Administration, relying on the health theme map of the Yangtze River Delta Government Map, launched a new crown vaccination point query service.

The general public can check the relevant information of the new crown vaccination site on the Yangtze River Delta Government Map, find the most convenient vaccination site around, and go to receive the second dose of the booster vaccine.

  On the 20th, China Business News learned from the Hefei multi-district community health service center that the city's second dose of booster vaccination has officially started.

The doses provided by different vaccination sites are different. Among them, some vaccination sites provide inhaled new crown vaccines for eligible booster immunization recipients, and some vaccination sites say that they only provide two types of inactivated vaccines, Kexing and Kangtai Biological.

  In Fuyang, another city in Anhui, a local district issued the "Notice on Comprehensively Carrying out Booster Inoculation of New Coronavirus Vaccines" on the 16th, which subdivided the second dose of booster injection into three categories: First, completed Inoculation of 3 doses of inactivated vaccines can optionally be given as a booster second dose of the new coronavirus vaccine; second, the adenovirus vector vaccine has been vaccinated twice (no distinction between intramuscular injection and inhalation, inhalation is not available for first-time vaccinators) , only adenovirus vector vaccines can be used for boosting; third, inactivated two doses + sequential booster vaccinations for the first dose continue to use the vaccine used for boosting the first dose [differentiate vaccine types (such as recombinant vaccines, adenovirus vector vaccines), not Differentiate manufacturers].

  "Three doses of Anhui Zhifeilong Coma Protein Recombinant (CHO cell) vaccine and people under 18 years of age do not need a second booster injection for the time being," the notice said.

  Not only in Anhui, China Business News called many vaccination units in Shenzhen, Shijiazhuang, Chongqing, Shanghai and other places as vaccinators on the 20th. The relevant staff all said that the current dose reserve for the second dose of booster immunization is sufficient , but the dosage is relatively limited.

  "Our fourth dose vaccination service is not limited to immune vulnerable groups. As long as you have not had the new crown recently, you can come to us to receive the fourth dose after making an appointment. However, if you have received the first three doses For inactivated vaccines, we are temporarily unable to provide sequential boosts." A staff member of a vaccination unit in Shenzhen told reporters.

  At this stage, the new coronavirus vaccines that have been approved for emergency use or conditional marketing in our country include four types: inactivated vaccines, recombinant protein vaccines, adenovirus vector vaccines and influenza virus vector vaccines.

  According to the implementation plan, all vaccines approved for conditional marketing or emergency use can be used for the second dose of booster immunization, but "sequential booster immunization should be given priority" or "use a strain containing Omicron or against Omicron Vaccines with good cross-immunity against the Rong strain".

  Sequential booster immunization refers to the use of vaccines with different technical routes for heterologous booster immunization.

A number of studies at home and abroad have shown that heterologous booster immunization with vaccines of different technical routes can obtain a higher level of neutralizing antibodies.

  Considering that most of the recipients in my country used three doses of inactivated vaccines during the early vaccination process, the recombinant protein vaccine, adenovirus vector vaccine or influenza virus vector vaccine can be selected for the second booster immunization. Either way, this is also the eight recommended inoculation combinations listed in the embodiment.

In addition, the implementation plan also recommends another vaccination method: "2 doses of CanSino intramuscular injection adenovirus vector vaccine + 1 dose of CanSino recombinant new coronavirus vaccine for inhalation".

  "This week, the number of people who came to consult was significantly more than those who had actually been vaccinated (the fourth shot)." The above-mentioned medical staff of a community hospital in Chongqing told reporters.

  She said that since late November, Chongqing has experienced a wave of infection peaks, and many local people have just "recovered from the sun."

Among these people, some people have "unbearable looking back" because of the infection experience, and some people hope to "superimpose the immune effect". There are many people who come to consult the "fourth shot", but these people do not meet the time interval requirements for the second dose of booster immunization.

  "The number of elderly people who have actually completed the fourth dose of vaccination is still relatively limited." The medical staff said that first of all, the number of elderly people who have completed booster immunization in the community is still very limited. Even if it is completed, few people will reach the 6-month interval Secondly, during the peak period of infection, there is a greater risk of cross-infection during vaccination. Some elderly families with comorbid underlying diseases will not choose to take the elderly into and out of the hospital at this time.

  Should "Yangkang" and non-immune vulnerable groups be hit?

  Up to now, my country has adjusted the interval between the booster vaccination of the new crown vaccine for the elderly and the basic full vaccination from the original 6 months to 3 months, but the time interval between the second dose of booster immunization and the first dose of booster immunization for any population All need to be more than 6 months old.

  For the "Yangkang" group, after the infection recovers, the time interval for re-boosting immunization is also recommended to be more than 6 months.

  Suo Luodan, director of the Immunization Institute of the Beijing Center for Disease Control and Prevention, mentioned in a science popularization on the second dose of booster immunization on the 19th that according to the current national technical guidelines for the use of new crown vaccines, it is rare to be reinfected within 6 months after a positive infection with the new crown virus The condition of the disease.

Those with previous COVID-19 infection (patients or asymptomatic infections) can receive one dose after 6 months on the basis of full notification.

  "The cycle of vaccination generally has two factors to measure. One is the degree of decline in the protective effect of the vaccine, that is, the duration of antibody maintenance after the latest vaccination, and the other is safety." A new crown virus research expert told Yicai Global.

  He said that for non-immune vulnerable people, if they have received three doses of vaccines, especially after experiencing an infection, the "memory" in immune B cells will persist even 6 months after the most recent antibody production , which means that the existing antibodies are still effective in preventing severe illness and death.

On the contrary, if the booster immunization is carried out again in a short period of time after the production of natural antibodies, it is equivalent to another shock to the human immune system, which is unnecessary and unsafe.

  In the opinion of the expert, there are two reasons why the elderly and other immune vulnerable groups need to be vaccinated with the "fourth shot": first, as time goes by, the level of neutralizing antibodies in the elderly declines more significantly; Second, these people are at risk of severe illness after being infected with the new coronavirus. Therefore, it is necessary to have a "relatively strongest immune protection" in the body.

  As for the reasons behind the “vaccination hesitation” mentioned by the above-mentioned grassroots vaccinators of some elderly groups, that is, at the moment when the number of positive infections increases sharply, vaccination may instead increase the risk of exposure. The expert believes that it really needs to be taken seriously.

But in theory, if you get infected when you get vaccinated or on the way home, the vaccine can still play a certain role in immune protection.

  So, is the new coronavirus vaccine only valid for 6 months?

What's next for COVID-19 vaccinations?

  Wang Huaqing, chief expert of the immunization program of the Chinese Center for Disease Control and Prevention, said at a press conference held by the Joint Prevention and Control Mechanism of the State Council on the 20th that the protective effect of the new crown virus vaccine after vaccination is that one will produce antibodies and the other will produce cellular immunity. Create immune memory.

After vaccination, antibody levels will decrease over time. In addition, as the virus mutates, immune escape is also enhanced, further weakening the effect of antibodies.

However, the effect of cellular immunity, especially in preventing severe illness and death, is relatively long-lasting.

  Studies have shown that through booster injections, on the one hand, the body's immune memory cells can be aroused, and on the other hand, antibody levels can also be increased, further consolidating the preventive effect on severe illness and death.

"Therefore, we still emphasize that those who have not completed the booster immunization, as long as they meet the vaccination requirements, should complete the booster immunization as soon as possible in accordance with the immunization procedures to achieve a better protective effect. Of course, we should systematically evaluate the effect of booster immunization in the future." Evaluate and continually refine immunization strategies."

  In the future, whether it is vaccine development or improvement of existing vaccines, Wang Huaqing said that we must start from two aspects: first, we must consolidate and achieve long-lasting and extensive protective immunity; second, we must start from blocking infection , to make further efforts to prevent transmission.