May 27, 2024

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Vaccine Knowledge Parents should Know

Vaccine Knowledge Parents should Know

Vaccine Knowledge Parents should Know.  Vaccines are the most economical, effective, safest, and most convenient scientific and technological invention for mankind to overcome major infectious diseases. Vaccination is the most cost-effective public health intervention to prevent and control infectious diseases.

Vaccine Knowledge Parents should Know

Since humans have mastered the principles and technology of vaccines, smallpox has been eliminated, measles, and polio have been eliminated worldwide, and the epidemic of pertussis, diphtheria, hepatitis A and other diseases have been effectively controlled. The current vaccine can prevent 2 million to 3 million annually. Of deaths.


01 Definition of vaccine

As the name implies, everyone knows that vaccines are organisms that are used to prevent and treat diseases made from microbial proteins, polysaccharides, nucleic acids, and other immunogenic biological materials (in vivo induction, active immunity) that are used in traditional methods or genetic engineering techniques. Products.

Vaccines can be monovalent or multivalent. A monovalent vaccine is a single strain containing a single antigen (such as measles vaccine), while a multivalent vaccine contains two or more strains/serotypes of the same antigen (such as influenza vaccine, HPV). Vaccine), the combination vaccine contains two or more antigens (such as DPT vaccine).

Note: There is no evidence that multiple antigens in the combined vaccine will increase the burden on the immune system and increase the probability of adverse reactions. The human immune system can simultaneously fight the immune response generated by millions of antigens. On the contrary, the combined vaccine reduces the occurrence of overall adverse reactions, so it is a good explanation that affected by the epidemic, it is safe and reliable for the vaccinator to vaccinate children with two or more vaccines at the same time.



02 Vaccine classification

For the general public, vaccines are divided into immunization program vaccines (free) and non-immunization program vaccines (other vaccines voluntarily vaccinated by citizens). Today we will talk about the classification according to the characteristics of vaccines, which are divided into four types: live attenuated Vaccines, inactivated vaccines (dead antigen), subunit vaccines (pure antigen), toxoid vaccines (inactivated toxin compounds).

1. Live attenuated vaccine

The toxins or bacteria are cultured for multiple generations to attenuate or weaken them, and retain the immunogenicity. The obtained vaccine microorganisms can increase in the recipients, thereby generating immunity, which usually does not lead to the occurrence of diseases, and natural infections. The immune response is almost the same.

Advantages: The first dose of live attenuated vaccine can usually produce protection, and the second dose can ensure seroconversion. For example, 95%-98% of the recipients can have an immune response after receiving the first dose of Japanese encephalitis vaccine. , Nearly 100% of the recipients can get immunity after receiving the second dose (the second dose is “insurance”). The immunization time of live attenuated vaccine is long, and booster immunization is not necessary. The exception is the oral polio vaccine, which requires multiple doses.

Disadvantages: Live attenuated vaccines are often unstable, resistant to heat, and light. They must be taken care of and transported carefully. Part of the toxicity may be restored when people with weakened immune systems are vaccinated, which may lead to vaccine-related diseases.

Common vaccines: leprosy, mumps, attenuated Japanese encephalitis, attenuated hepatitis A, chickenpox, oral polio vaccine, etc.


2. Inactivated vaccine

Use culture medium to cultivate viruses or bacteria, and then inactivate them with heat or chemical substances (mostly formalin). It will not replicate and increase in the recipient’s body. Therefore, the immune deficiency will not cause disease when inoculated. (E.g. HIV-positive children).

Advantages: It is safer, does not cause disease, is often not affected by circulating antibodies, and is more stable.
Disadvantages: There are many times of inoculation, and more than 2-3 times are required. Generally speaking, the first dose only activates the immune system and usually does not produce immunity. Protective immunity will only be generated after multiple doses. The duration of immunity is short. Therefore, some inactivated vaccines require regular supplements. Times.
Common vaccines: IPV, EV71, hemorrhagic fever, inactivated Japanese encephalitis, inactivated hepatitis A vaccine, etc.


3. Subunit vaccine

The whole pathogen is cultivated in the medium, and then further processed and purified to retain only certain components of the vaccine species (such as protein, bacterial capsular polysaccharide).

Protein vaccine:

Vaccines made by isolating and extracting immunogenic proteins from pathogens. For example, yeast hepatitis B vaccine inserts hepatitis B virus genes into yeast cells. The modified yeast cells can produce a large amount of hepatitis B surface antigens, which are purified and extracted. to make.

  • Advantages: Stable and safe.
  • Disadvantages: There are many inoculation doses, more than 2-3 doses are required.
  • Common vaccines: yeast hepatitis B vaccine, whooping cough vaccine, etc.

Polysaccharide vaccine:

Vaccines made by isolating and extracting bacterial capsular polysaccharides from pathogens, containing the polysaccharide coat or shell of capsular bacteria, are purified and non-infectious vaccines.

  • Advantages: stable and safe.
  • Disadvantages: The effect of vaccination is not good for children under two years of age, because children under two years of age have an imperfect immune system and cannot produce a good immune response to polysaccharide antigens produced through T cell-independent mechanisms.
  • Common vaccines: Group A polysaccharides, Group A+C polysaccharides, 23-valent pneumonia vaccine, etc.

Combination vaccine:

The combination of polysaccharides and protein vaccines combines the advantages of protein vaccines and polysaccharide vaccines. Commonly used are A+C group combined vaccines, AC group+HIB combined vaccines, and so on.

Toxoid vaccine:

A vaccine made through the purification of toxins and chemical treatment (commonly used formaldehyde). In some bacterial infections (such as diphtheria, tetanus), the clinical manifestations of the disease are not caused by the bacteria themselves, but by the toxins they secrete.

  • Advantages: Toxoid vaccines are no longer toxic, and vaccination is safe and reliable. Tetanus vaccines are common.



03 Other ingredients in the vaccine


Adding some in the vaccine production process can enhance the strength and/or durability of the immune response, so as to reduce the dose of immunogen per dose, or to reduce the total doses of vaccination required for immunity. Common adjuvants such as aluminum hydroxide, aluminum phosphate, aluminum potassium sulfate, etc., mainly increase the immune response to protein.


To prevent the tissue culture cells for virus growth from being contaminated by bacteria, neomycin is commonly added to MMR vaccine and IPV vaccine.


Adding chemicals (such as thimerosal) to inactivated vaccines or subunit vaccines can inactivate viruses, detoxify bacterial toxins, and prevent serious secondary infections caused by bacterial and fungal contamination.


Adding chemical substances to vaccines, such as freeze-dried vaccines, in order to stabilize the antigen and prevent the antigen from attaching to the surface of the ampoule, causing the loss of the immune prototype, often adding aluminum salt, sodium salt, lactose, human serum protein and various animal proteins Wait.

Note: The other ingredients in the vaccine are removed in the subsequent production process, but very few of its ingredients may remain in the final product, which may have adverse consequences for people who are allergic to the residue.


04 Phase IV clinical trials of vaccine development

Phase I: Clinical pharmacology and human safety test to observe human metabolism and safety
Phase II: Double-blind controlled human trial to observe effectiveness and safety
Phase III: Multi-base clinical trials, expanded observation of effectiveness and safety
Stage IV: monitor after application to observe the effectiveness and adverse reactions during widespread use

Today we learned about vaccines together. The development and production of a new vaccine to its widespread use is a complicated and long process. The application of vaccines not only reduces the incidence and mortality of infectious diseases, but also HPV vaccines and influenza vaccines. , Pneumonia vaccines, etc. can also have direct or indirect preventive effects on some cancers and chronic diseases.

At the same time, the key to achieving excellent results of vaccination lies in the high vaccination rate. The high vaccination rate of the population can obtain the effect of herd immunity and reduce the spread of vaccines against diseases.

In recent years, with the impact of various vaccine incidents, the people have insufficient confidence in the safety of vaccines. It is hoped that through today’s study, everyone can have a new understanding of vaccines, understand the advantages and disadvantages of various vaccines, and be able to choose vaccines correctly. Effectively protect the health of children and adults and reduce medical expenses.

(source:internet, reference only)

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