How does the magic vaccine fight the pathogen?

How does the magic vaccine fight the pathogen?  The previous life of the vaccine came from a gift given to humans by dairy cows in the 18th century. It was discovered by the British doctor Jenner, known as the “father of immunology”. He discovered that the milkmaid never had chickenpox and invented the miraculous “cowpox” Vaccines and promotion of vaccinia have eliminated the stubborn enemy of smallpox. It also made smallpox the first virus to be eliminated by humans. Therefore, the vaccine is a great invention in the history of human medical and health development.

Starting from the vaccinia vaccine against smallpox, medical scientists through tireless research and experimentation have continuously developed vaccines with a higher safety factor and a more convenient vaccination method to help people resist polio, measles, Japanese encephalitis, meningococcal, typhoid, and plague. , Rabies and other diseases that seriously threaten human health.

But some people wonder whether a small vaccine is so magical? Here, Sister Disease Control will talk to you about how this magical vaccine fights pathogens? What is the herd immunity barrier? How to form group protection?

How does the magic vaccine fight the pathogen?

Vaccines are “snipers” against pathogens. The most important component in the vaccine is the antigen, which is the “pretender” of the pathogen. After vaccination, the antigen component in the vaccine will stimulate the body’s immune system, so that it can be identified, activated, proliferated, and differentiated in an organized and targeted manner. When immune cells are produced, this process is called immunity. Immunity is the body’s defense against infection. Vaccination is also called immunization. These immune cells (B cells, T cells, and helper T cells) serve as a “stand-by army” and have immune memory functions.

Vaccination is similar to a fire simulation exercise. For example, in a school, the general steps of a fire simulation drill are from the sounding of the alarm to the orderly evacuation of students in the corridor, and then to queuing by class outside the classroom. After the students have gone through the drill, if a fire does happen, they will know how to respond safely and quickly. Vaccine training the immune system against certain diseases is similar to training students through fire drills in schools. Vaccination is a “simulation exercise” before a pathogen enters the human body. When a real pathogen invades the human body, the immune system can recognize it and eliminate it.

Common types of vaccines

(1) Live attenuated vaccine

Live attenuated vaccine means that after a live pathogen is cultured, multi-generation reproduction and treatment, the virulence is weakened, and only a certain degree of immunogenicity and reproductive ability is retained, but no pathogenicity. After being made into a vaccine to inoculate the human body, the body produces a subclinical infection and gains immunity. Live attenuated vaccines can produce cellular immunity and humoral immunity after inoculation, and live attenuated vaccines can also produce mucosal immunity after oral or nasal spray.

The general characteristics of this type of vaccine are: strong and long-lasting immunity. In addition to oral vaccines, live attenuated vaccines are usually effective after one dose. The disadvantage is that live attenuated vaccines have the potential for reversion of virulence, and may have serious reactions to immunodeficiency patients (such as HIV infection) or patients receiving immunosuppressive therapy. Currently, live attenuated vaccines in clinical use include BCG, MMR, oral polio, nasal flu, varicella, rotavirus, and shingles vaccines.

(2) Inactivated vaccine

Inactivated vaccines are to first cultivate viruses or bacteria, and then inactivate them by heating or chemical methods to lose their virulence, but still retain their immunogenicity. After vaccination, they can produce an immune response based on humoral immunity. .

The general characteristics of this type of vaccine are: “safe” and “effective”. The disadvantage is that it usually requires larger doses of injections, multiple vaccination, and regular booster vaccination to increase or enhance the antibody titer, the resulting immune effect is maintained for a short time, and usually does not produce cellular immunity. Inactivated vaccines currently in use include viral vaccines (influenza, polio, rabies, hepatitis A, etc.) and bacterial vaccines (pertussis, typhoid fever, etc.).

(3) Genetic engineering vaccine

Use bioengineering technology to insert effective specific antigen genes of bacteria or viruses into vectors that are prone to proliferation (bacteria or cells). When the vector multiplies, effective specific antigens can be expressed, and the vaccines can be made. China now uses recombinant yeast hepatitis B vaccine and hepatitis B genetic engineering (CHO) vaccine.

Because the vaccine is prepared through attenuation, inactivation, or recombinant technology, it is weakened, or killed, or partly, which can trigger the immune system to produce neutralizing antibodies to kill pathogens, and lose the pathogenicity. ability. At the same time, the vaccine also contains adjuvants and other ingredients to stabilize it. Therefore, vaccines produced by modern medical technology are safe and effective.

What is the herd immunity barrier? How to form group protection?

When most people are vaccinated, these people not only get immune protection, but also protect the surrounding individuals who have not been vaccinated. This is the population immune barrier formed by vaccination.

The ability of a group to resist certain infections and transmissions is based on the proportion of people with resistance levels in this group. This proportion may be different for different diseases, but it is certain that the higher the proportion of resistant people in the population, the better the overall population protection effect. At present, routine immunization program vaccines have maintained a high coverage rate, and an immune barrier has been established for the population. Infectious diseases preventable by vaccines such as polio, measles, Japanese encephalitis and meningitis have been effectively controlled.

Large-scale vaccination of COVID-19 vaccine forms herd immunity and helps prevent and control the epidemic

On December 19, 2020, the Joint Prevention and Control Mechanism of the State Council of China held a press conference officially released the vaccination strategy will be implemented in two steps:

• The first step is mainly for some key populations, including those who are engaged in import cold chain, port quarantine, ship piloting, aviation air service, fresh food market, public transportation, medical disease control, and other staff with high risk of infection, as well as those who go to medium and high risk countries or regions People who go to work or study;
• The second step is to carry out vaccination for the general population as the vaccine is approved for marketing or the production of vaccines is gradually increased.

At present, many countries have begun to vaccinate the people with the new coronavirus free of charge. Through the orderly implementation of preventive vaccination, eligible people can achieve “every need”, which will gradually build an immune barrier for the population and effectively block the spread of the new coronavirus. . However, theCOVID-19 vaccine is a gradual process, please wait patiently, please pay attention to the relevant notices in various places.

I hope that we can finally defeat the COVID-19 epidemic through prevention and control measures such as immunization, wearing masks, washing hands frequently, frequent ventilation, maintaining a safe social distance, and daily disinfection!

(source:internet, reference only)

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