What is the Covid-19 vaccine?

Covid-19 vaccine is a type of vaccine against acute respiratory infections, which helps prevent Corona virus. Currently, there have been many units that have announced successful production of a vaccine against Corona virus with quite positive effects.

At the end of February 2020, the World Health Organization (WHO) expressed concern about a vaccine against acute respiratory infections caused by Sars-Cov-2 virus that could be successfully produced within 18 months. But just 8 months later, there were more than 320 candidates participating in the global race to research and test a Covid-19 vaccine, making Covid-19 the fastest research vaccine in history. . (first)

In November 2020, 56 vaccine candidates are in the process of clinical research, in which, the candidate of AstraZeneca is one of the Covid-19 vaccines that rose to the top of the race when the manufacturer announced positive results from the analysis of phase III vaccine clinical trials, and offered bright hope that promises to be ready to provide 3 billion doses of vaccine to people globally.

The search for a safe and effective vaccine against the risk of Covid-19 infection is a top concern today. Understanding the importance of Covid-19 vaccine for public health, VNVC vaccination system has continuously made efforts to approach many famous vaccine companies in the world in order to realize the dream of bringing Covid vaccine back to Vietnam. South, and the dream came true.

For the first and only time in Vietnam, the VNVC system of children and adults vaccination centers officially brought AstraZeneca’s Covid-19 vaccine to Vietnam. The vaccine is produced by Oxford University and the world’s leading pharmaceutical group (United Kingdom).

This is a vaccine with many advantages, high immunogenicity, safety, reasonable price, proven effective beyond the expectations of the World Health Organization (WHO), expected to stop the epidemic. acute respiratory infection caused by Sars-Cov-2 virus in Vietnam and contributed to extinguishing the global Covid-19 pandemic.

Mechanism of immunogenicity of the Covid-19 vaccine

1. Passive immunity

Passive immunity against Covid-19 can be achieved by sera from patients who have recovered from Sars-Cov-2 virus infection, which contain large amounts of immune antibodies, from super-immune globulin – eg. such as cytomegalovirus immunoglobulin (CMVIG) collected from various donors or with monoclonal neutralizing antibodies.

2. Active immunity

Currently, there are more than 100 Covid-19 vaccines in the preclinical stages of development. Vaccines work by different mechanisms to induce immunity, but with all Covid-19 vaccines, the common mechanism is that in addition to producing antibodies against the virus, the vaccine can also produces memory T and B lymphocytes to fight pathogens, fighting them off if attacked in the future.

Until now, experts are still figuring out how long these memory cells protect the body from the Sars-Cov-2 virus.

For COVID-19 Vaccine AstraZeneca, the body develops immunity, preventing the causative agent of the SARS-CoV-2 virus. Different vaccines will have different effects on the body’s immune response, but one thing in common in how vaccines work is that in addition to creating antibodies against the virus, vaccines also have can create immune cells, called T lymphocytes, memory B lymphocytes to fight “invaders” – viruses in the future.

AstraZeneca’s COVID-19 vaccine is vector-based, i.e. a vaccine using chimpanzee’s replicating adenovirus, based on an attenuated version of the adenovirus (swine flu virus that causes disease in chimpanzees). sperm), containing the genetic material of the spike protein on the surface of the SARS-CoV-2 virus that causes COVID-19 called Spike or S. Protein. On the other hand, Spike is the pioneer ingredient that opens the way for the SARS-CoV-2 virus to invade the human body and is also the target of the immune system’s attack when the SARS-CoV-2 virus invades.

After vaccination, spike surface protein is produced, the immune system continues to make memory cells. These cells will detect the SARS-CoV-2 virus if it attacks the body in the future, by recognizing the spike protein on the surface of the virus. If immune cells pass through the SARS-CoV-2 virus in the body, they will produce many antibodies and T cells very quickly, which prevents the virus from spreading and reduces complications and dangers from the disease. caused by COVID-19.

One of the unique features of the race to produce a corona vaccine is the difference between vaccine candidates and vaccine production technology. Accordingly, current Covid-19 vaccines are being produced by three mechanisms:

mRNA vaccine: The vaccine introduces the synthesized RNA molecule into the body’s cells. Once inside the cell, the vaccine’s synthetic mRNA acts as a native mRNA, initiating the synthesis of a new protein (which is normally synthesized by the virus). This new protein in turn triggers the body’s adaptive immune response against the viral protein. Thus, the body receives the vaccine, both creating antigen (virus protein) and creating an immune response against this protein (antibody + cellular response).
Protein Vaccine: This vaccine consists of purified protein fragments of the Sars-Cov-2 virus. After the vaccine is injected into the body, the immune system recognizes that this protein is an “invader” and the immune response produces antibodies. At the same time, vaccines help cells remember to recognize pathogens, proceed to destroy them if attacked in the future.
Vector vaccines: Vector-based vaccines differ from most conventional vaccines in that they do not actually contain antigens, but use the body’s own cells to produce them. Vaccines are manufactured using a modified virus (vector) to deliver the genetic code for the antigen. For the Sars-Cov-2 virus vaccine, the genetic code is spike proteins on the surface of the virus. When the vaccine is injected into the body, it stimulates the body to produce a large amount of antigen. These antigens will trigger an immune response. Vaccines mimic what happens during natural infection with certain pathogens – especially viruses. This has the advantage of triggering a strong cellular immune response by T cells as well as antibody production by B cells.
AstraZeneca’s Covid-19 vaccine brought to Vietnam by the VNVC vaccination system is a vector vaccine. AstraZeneca’s virus vector technology is a new, versatile, high-performance technology that does not depend on the culture of the entire pathogen, it is also evaluated as suitable for production of anti-virus vaccines. with global pandemics.


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