Are there any seedlings in Beijing Kexing?

Beijing Kexing Inactivated Vaccine: Beijing Kexing Zhongwei Biotechnology Co., Ltd., COVID-19 Inactivated Vaccine was approved for marketing on February 5, and Kexing Vaccine has been injected in many countries and regions in the world since 200211.

There are also rumors on the internet that Kexing vaccine has been discontinued, and it is impossible to inject Kexing vaccine now. In fact, this statement is a rumor At present, Kexing vaccine can still be vaccinated normally.

The decrease in the number of vaccines in Kexing COVID-19 may be due to the small quantity purchased by the state. However, according to the technical guidelines for vaccination in COVID-19, at this stage, it is recommended that everyone use the same vaccine and complete three doses of vaccination.

If you encounter special circumstances, such as the vaccine from the same manufacturer can't continue to supply, or the audience can't use the same vaccine product to complete the vaccination, you can also use vaccines produced by other industries.

Advantages and disadvantages of vaccines

First generation vaccine: including attenuated live vaccine and inactivated vaccine.

Advantages of live attenuated vaccine: Because it is a live vaccine, it can continuously stimulate the body to produce humoral immunity and cellular immune response after inoculation, with good immune effect and long action time. In addition, because it is a live virus/bacteria, it can directly induce immune response without the purification of adjuvant and antigen protein. So to sum up, the effect is good and the process is simple.

Disadvantages of live attenuated vaccine: the pathogen with weakened virulence may recover its strong pathogenicity through mutation, that is, the phenomenon of "virulence reversal". For example, there have been many sporadic cases of virulence reversal of live attenuated poliomyelitis vaccine, resulting in illness of vaccinated children. In addition, the requirements for preservation conditions are relatively high, and the whole process of cold chain transportation is needed for preservation. It is for this reason that many countries have gradually given up live attenuated vaccines.

Inactivated vaccine can be understood as the corpse of a virus. When these virus corpses are injected into human body, there is no genetic material, or the genetic material has been destroyed, so it cannot cause human infection. The protein shell of the virus can induce specific immune response in human body, thus making people have corresponding disease immunity. For example, hepatitis B vaccine and influenza split vaccine, which have been used for a long time in China, are inactivated vaccines.

Advantages of inactivated vaccine: it is safer than attenuated vaccine and there is no risk of reversion of virulence.

Disadvantages of inactivated vaccine: it only induces humoral immune response, but the cells responsible for synthesizing antibodies can only keep the "memory" of this pathogen for a certain period of time, and the immunity will be ineffective after "forgetting". Because the immune effect is weak, it needs to be vaccinated several times (basic strengthening), and the protection time of antibody production is short, so it needs to be vaccinated again after 3-5 years. For example, hepatitis B vaccine is immunized once at birth, once a month and once every six months. After adulthood, it is necessary to strengthen the injection in time according to the five results of hepatitis B in order to maintain enough antibody titer in the body and form an effective defense against hepatitis B virus.

The second generation vaccine: the main representatives are subunit vaccine and recombinant gene vaccine.

Subunit vaccine: A vaccine made by amplifying a large number of viruses from chicken embryos or tool cells, then extracting the special protein structure of pathogens through chemical decomposition or controlled protein hydrolysis, and screening out the immune active fragments. Attention should be paid to distinguish it from the split vaccine in the previous generation inactivated vaccine. The split vaccine is still protein, while the subunit vaccine is a polypeptide fragment produced by further hydrolysis of protein, which can induce immune response. Subunit vaccine is a vaccine made of the main protective immunogen of pathogenic bacteria, so it is also called component vaccine.

Recombinant gene vaccine: Whether it is protein produced by cracking pathogens or subunits produced by further decomposition, these hydrolysates of protein or protein which can induce immune response are all synthesized by nucleic acids. Therefore, scientists began to try to implant the gene fragments leading to protein synthesis into tool cells (gene recombination technology), so that these tool cells can produce the corresponding protein in large quantities. Then these proteins are collected and purified to obtain recombinant gene vaccine. Commonly used tool cells are Escherichia coli, yeast and so on. Can be rapidly mass-produced through a simple and efficient fermentation industry, and the cost is lower than that of a unit vaccine.

The third generation vaccine: mainly includes recombinant virus vector vaccine and nucleic acid vaccine.

Recombinant virus vector vaccine: find out the gene fragment responsible for inducing the synthesis of immunogenic protein/subunit in the virus, and then graft it to a well-known virus (such as adenovirus) that is non-pathogenic or minimally pathogenic. After exploration, a large number of protein/subunits which can induce immune response were synthesized by carrying gene fragments into human cells with vector virus. This is equivalent to combining the advantages of live attenuated vaccine and subunit vaccine and avoiding their disadvantages.