Inactivated corpuscular vaccines. Vaccines

Live viral vaccines- these are, as a rule, artificially weakened through cultivation or natural avirulent or weakly virulent immunogenic strains of the virus, which, when multiplying in a naturally susceptible organism, do not show an increase in virulence and have lost the ability to horizontal transmission.

Safe, highly immunogenic live vaccines are the best of all existing viral vaccines. The use of many of them has yielded brilliant results in the fight against the most dangerous viral diseases of humans and animals. The effectiveness of live vaccines is based on simulating subclinical infection. Live vaccines induce an immune response to each protective antigen of the virus.

Main advantage live vaccines considered to be the activation of all parts of the immune system, causing a balanced immune response (systemic and local, immunoglobulin and cellular). This is of particular importance in those infections where cellular immunity plays an important role, as well as in infections of the mucous membranes where both systemic and local immunity are required. Topical application of live vaccines is generally more effective in stimulating a local response in unprimed hosts than inactivated vaccines administered parenterally.

Ideally, vaccination should repeat immunological natural infection stimuli, minimizing unwanted effects. It should induce intense long-lasting immunity when administered in a small dose. Its administration, as a rule, should not be accompanied by a weak, short-term general and local reaction. Although, after the administration of a live vaccine, it is sometimes possible for a small proportion of recipients to develop certain mild clinical signs that resemble a mild course of a natural disease. Live vaccines meet these requirements better than others and, in addition, are characterized by low cost and ease of administration in a variety of ways.

Vaccine viral strains must have genetic and phenotypic stability. Their survival rate in the grafted organism must be pronounced, but their ability to reproduce must be limited. Vaccine strains are significantly less invasive than their virulent predecessors. This is due in large part to their partially limited replication at the site of entry and in the target organs of the natural host. Replication of vaccine strains in the body is more easily limited by natural nonspecific protective mechanisms. Vaccine strains multiply in the vaccinated organism until its protective mechanisms inhibit their development.
During this time, such an amount is formed antigen, which significantly exceeds it when administered with an inactivated vaccine.

For attenuation of viruses Typically, virus passages in an unnatural host or cell culture, passages at low temperatures, and mutagenesis followed by selection of mutants with an altered phenotype are used.

Most modern live vaccines, used for the prevention of infectious diseases in humans and animals, are obtained by passages of a virulent virus in a heterologous host (animals, chicken embryos, various cell cultures). Viruses attenuated in a foreign organism acquire multiple mutations in the genome that prevent the reversion of virulence properties.

Currently widely used in practice live vaccines against many viral diseases of humans (poliomyelitis, yellow fever, influenza, measles, rubella, mumps, etc.) and animals (rinder, swine, carnivore, rabies, herpes, picorna, coronavirus and other diseases). However, it has not yet been possible to obtain effective vaccines against a number of viral diseases of humans (AIDS, parainfluenza, respiratory syncytial infection, dengue virus infection, and others) and animals (African swine fever, equine infectious anemia, and others).

There are many examples that traditional virus attenuation methods have not yet exhausted their potential and continue to play a significant role in the development of live vaccines. However, their importance is gradually decreasing as the use of new technology for constructing vaccine strains increases. Despite significant progress in this area, the principles of obtaining live viral vaccines laid down by L. Pasteur have still not lost their relevance.

LIVE VACCINES

live vaccines, vaccines prepared from strains of pathogenic microbes with weakened virulence. J.v. cause a benign infectious process in the body - a vaccine reaction, leading to the formation of immunity against this infection. See also .

Veterinary encyclopedic dictionary. - M.: "Soviet Encyclopedia". Editor-in-Chief V.P. Shishkov. 1981 .

See what “LIVE VACCINES” is in other dictionaries:

Live vaccines- Live vaccines are produced on the basis of antigens of pathogens of infectious diseases, attenuated under artificial or natural conditions. These vaccines do not cause a clinical picture of the disease, but are capable of forming lasting immunity...... ... Official terminology

live virus vaccines- Vaccines containing live attenuated viruses. [English-Russian glossary of basic terms in vaccinology and immunization. World Health Organization, 2009] Topics vaccinology, immunization EN live virus vaccines ...

live bacterial vaccines- Vaccines consisting of live, weakened bacteria. [English-Russian glossary of basic terms in vaccinology and immunization. World Health Organization, 2009] Topics vaccinology, immunization EN live bacteria vaccines ... Technical Translator's Guide

Vaccines- one of the types of medical immunobiological preparations (MIBP), intended for immunoprophylaxis of infectious diseases. Vaccines containing one component are called monovaccines, in contrast to associated vaccines containing... ... Dictionary-reference book of terms of normative and technical documentation

live attenuated viral vaccines- - [English-Russian glossary of basic terms on vaccinology and immunization. World Health Organization, 2009] Topics vaccinology, immunization EN live attenuated virus vaccines ... Technical Translator's Guide

Vaccines- preparations from microorganisms used to artificially create active specific acquired immunity against certain types of microorganisms or the toxins they secrete. V. proposed for use in humans should... ... Dictionary of microbiology

- (from Latin vaccina cow), specific preparations obtained from microorganisms and their metabolic products and used for active immunization (vaccination) of animals for the purpose of preventing infectious diseases and treatment.… …

- (from the Greek anti prefix meaning opposition, and the Latin rabies rabies), live and inactivated vaccines used to immunize animals against rabies. They are prepared from chicken embryo tissue, brain tissue... ... Veterinary encyclopedic dictionary

Vaccine- This term has other meanings, see Vaccine (meanings). A vaccine (from the Latin vacca cow) is a medical or veterinary drug intended to create immunity to infectious diseases. The vaccine is being manufactured... ... Wikipedia

VACCINATION- VACCINATION, VACCINES. Vaccination (from the Latin vacca cow; hence vaccine cowpox) is a method by which the body is artificially given increased immunity to any infection; the materials that are used for... Great Medical Encyclopedia

Despite the invention of numerous medications with a good indicator of effectiveness, vaccination still continues to be the only reliable way to prevent certain infectious diseases.

In order to protect the child’s body from the effects of pathological microflora, various options for the vaccination composition are used to achieve the desired result. However, the living ones continue to be the most effective.

Technology for producing live vaccines

A live vaccine is a drug produced in the form of a suspension or dry powder substance, for dissolution of which water is used for injection.

Live vaccinations contain weakened pathogens that have a full list of characteristics of a full-fledged infectious agent that a child’s body can encounter in real life.

Such compositions form resistance to the effects of an infectious pathogen even after one administration, and therefore are considered the most effective compared to analogues of other types of vaccinations.

The main components in such vaccines are pathogenic bacteria that have been weakened or purified in the laboratory. The live vaccine composition is administered by injection. Aerosol or intranasal administration is also allowed.

Live vaccines require strict storage conditions. This is necessary for microorganisms to preserve the full range of properties.

Mechanism of action

A live vaccine contains weakened pathogens. Since we are talking about microorganisms that have undergone purification, they are not capable of developing a full-fledged infectious disease.

But their strength is quite enough to provoke the correct reaction of the immune system. After getting inside, the pathogenic microflora begins its destructive effect, as a result of which the body actively produces antibodies to the virus that got inside.

In this way, a reliable protective internal barrier is formed against the infectious agent. Despite the proven safety of this type of vaccination, the attitude towards the living among specialists continues to be twofold. A certain number of medical workers continue to consider this type of vaccination.

Some doctors believe that such a vaccine cannot be given to a child, since a child’s fragile body may not be able to cope even with the effects of a weakened virus, which can result in a full-fledged infectious disease.

However, such an opinion continues to remain an opinion as long as a sufficient number of children receive reliable and long-term protection from infections by introducing them to a live vaccination composition.

Types and their characteristics

Today in medicine the following types of vaccines are used to obtain the desired response from the immune system:

1. live vaccines. We have already said that such drugs contain live pathogens of infectious diseases that have been purified in a laboratory. Such vaccination compositions are the most difficult from a medical point of view, since they are capable of exerting maximum pressure on the body compared to other analogues. Such vaccinations are stored under strictly specified conditions;
2. chemical vaccines. It is created by extracting antigens to it from a virus cell. Such drugs make it possible to vaccinate children of different ages and in different weight categories;
3. corpuscular vaccines. Such vaccinations contain killed cells of pathogenic microflora, due to which the impact of the infectious agent on the child’s body is minimal. But at the same time, the body’s immune system responds to the pathogen properly, producing antibodies against the effects of pathogenic microorganisms. Due to the use of dead pathogenic agents, the effect of using a corpuscular vaccine will be weaker and shorter than after using a live analogue. Therefore, in this case, prompt revaccination will be required. The storage conditions for this type of vaccine are less stringent. To preserve the basic properties of the composition, it is enough not to freeze the grafting composition.

The live vaccine is the most effective in terms of the duration of the effect obtained.

Features of application

In addition to strict adherence to storage rules, live vaccines also require maintaining intervals between procedures.

Vaccinations should be carried out at intervals of at least 1 month.

Otherwise, side effects from the immune system may follow, and the result obtained will be weak, which will not provide the desired protective effect.

The use of a live vaccination composition that has previously been frozen or transported in open packaging is strictly prohibited.

Which vaccines are considered live - complete list

Live preparations are not always used; they are used for the purpose of immunization against the following ailments:

• Q fever;
• some others.

This list includes both mandatory vaccines and voluntary ones, which are carried out either at the request of parents or in case of urgent need (for example, during an outbreak of an epidemic).

List of advantages

Despite the fears of doctors, live vaccine preparations still have a good set of advantages that make their use justified:

• the possibility of using small vaccination doses and a single administration of the drug;
• longer and stronger immune system response;
• the possibility of administration not only subcutaneously and intramuscularly, but also orally or aerosolly, as well as intranasally;
• rapid formation of a reaction from the immune system;
• ease of manufacture;
• affordable price.

The listed advantages make the use of living compounds convenient and very effective.

What is the disadvantage of using attenuated drugs?

Attenuated (or weakened) drugs are not ideal; they, like any other medical product, have their drawbacks, including:

• possible occurrence of complications in children and adults with weakened immune systems;
• long period of obtaining weakened strains;
• high probability of damage to the vaccination composition due to improper storage, transportation or use;
• the possibility of introducing latent viruses into the body.

Due to these disadvantages, many experts do not recommend immunization using live vaccine compounds.

How is the immune response characterized?

After the introduction of a living composition into the body, a standard immune response is formed in the form of the production of antibodies by the protective system against the infectious pathogen. As a rule, after using a live vaccine, the formation of an immune system response occurs quite quickly.

The body almost instantly begins to react to an infectious agent that has entered inside. Thanks to this point, a person receives protection against infection approximately 2 times faster than after using other types of vaccination compositions.

In some cases, the immune reaction is accompanied by the appearance of weakness and drowsiness, as well as lethargy, loss of appetite and some other manifestations. Similar symptoms after using live vaccine preparations are also considered normal.

Video on the topic

About the pros and cons of live and dead vaccines in the video:

Whether or not to use a live vaccine to immunize your child is a personal decision for each parent. But do not forget that if you compare the side effects of the vaccination and the complications caused by a full-fledged infection, the latter can cause more harm to the child’s body, even causing disability and.

1 . By purpose vaccines are divided into preventive and therapeutic.

According to the nature of the microorganisms from which they are created,there are wakiins:

Bacterial;

Viral;

Rickettsial.

Exist mono- And polyvaccines - respectively prepared from one or more pathogens.

By cooking methoddifferentiate between vaccines:

Combined.

To increase immunogenicity to vaccines sometimes they add various types adjuvants(aluminum-potassium alum, aluminum hydroxide or phosphate, oil emulsion), creating a depot of antigens or stimulating phagocytosis and thus increasing the foreignness of the antigen for the recipient.

2. Live vaccines contain live attenuated strains of pathogens with sharply reduced virulence or strains of microorganisms that are non-pathogenic to humans and closely related to the pathogen in antigen terms (divergent strains). These include recombinant(genetically engineered) vaccines containing vector strains of non-pathogenic bacteria/viruses (genes responsible for the synthesis of protective antigens of certain pathogens have been introduced into them using genetic engineering methods).

Examples of genetically engineered vaccines include the hepatitis B vaccine, Engerix B, and the rubella measles vaccine, Recombivax NV.

Because the live vaccines contain strains of pathogenic microorganisms with sharply reduced virulence, then, in essence, they reproduce a mild infection in the human body, but not an infectious disease, during which the same defense mechanisms are formed and activated as during the development of post-infectious immunity. In this regard, live vaccines, as a rule, create quite intense and long-lasting immunity.

On the other hand, for the same reason, the use of live vaccines against the background of immunodeficiency states (especially in children) can cause severe infectious complications.

For example, a disease defined by clinicians as BCGitis after administration of the BCG vaccine.

Live wakiins are used for prevention:

Tuberculosis;

Particularly dangerous infections (plague, anthrax, tularemia, brucellosis);

Flu, measles, rabies (anti-rabies);

Mumps, smallpox, polio (Seibin-Smorodintsev-Chumakov vaccine);

Yellow fever, rubella measles;

Q fever.

3. Killed vaccines contain killed pathogen cultures(whole cell, whole virion). They are prepared from microorganisms inactivated by heating (heated), ultraviolet rays, chemicals (formalin - formol, phenol - carbolic, alcohol - alcohol, etc.) under conditions that exclude denaturation of antigens. The immunogenicity of killed vaccines is lower than that of live ones. Therefore, the immunity they evoke is short-lived and relatively less intense. Killed wakiins are used for prevention:

Whooping cough, leptospirosis,

Typhoid fever, paratyphoid A and B,

Cholera, tick-borne encephalitis,

Poliomyelitis (Salk vaccine), hepatitis A.

TO killed vaccines include and chemical vaccines, containing certain chemical components of pathogens that are immunogenic (subcellular, subvirion). Since they contain only individual components of bacterial cells or virions that are directly immunogenic, chemical vaccines are less reactogenic and can be used even in preschool children. Also known anti-idiotypic vaccines that are also classified as killed vaccines. These are antibodies to one or another idiotype of human antibodies (anti-antibodies). Their active center is similar to the determinant group of the antigen that caused the formation of the corresponding idiotype.

4. To combination vaccines include artificial vaccines.

They are preparations consisting of microbial antigenic component(usually an isolated and purified or artificially synthesized pathogen antigen) and synthetic polyions(polyacrylic acid, etc.) - powerful stimulators of the immune response. They differ from chemically killed vaccines in the content of these substances. The first such domestic vaccine is influenza polymer-subunit (“Grippol”), developed at the Institute of Immunology, has already been introduced into Russian healthcare practice. For specific prevention of infectious diseases whose pathogens produce exotoxin, toxoids are used.

Anatoxin - it is an exotoxin, devoid of toxic properties, but retaining antigenic properties. Unlike vaccines, when used in humans, antimicrobial immunity, with the introduction of toxoids is formed antitoxic immunity, since they induce the synthesis of antitoxic antibodies - antitoxins.

Currently applied:

Diphtheria;

Tetanus;

Botulinum;

Staphylococcal toxoids;

Cholerogen toxoid.

Examples of associated vaccinesare:

- DTP vaccine(adsorbed pertussis-diphtheria-tetanus vaccine), in which the pertussis component is represented by killed pertussis vaccine, and diphtheria and tetanus by the corresponding toxoids;

- TAVTe vaccine, containing O-antigens of typhoid, paratyphoid A- and B-bacteria and tetanus toxoid; typhoid chemical vaccine with sextaanatoxin (a mixture of toxoids of Clostridium botulism types A, B, E, Clostridia tetanus, Clostridium perfringens type A and edematiens - the last 2 microorganisms are the most common causative agents of gas gangrene), etc.

At the same time, DPT (diphtheria-tetanus toxoid), often used instead of DTP when vaccinating children, is simply a combination drug and not an associated vaccine, since it contains only toxoids.

Vaccines are preparations intended to create active immunity in the body of vaccinated people or animals.

The main active principle of each vaccine is an immunogen, i.e. a corpuscular or dissolved substance that carries chemical structures similar to the components of the pathogen responsible for the production of immunity.

• Depending on the nature of the immunogen, vaccines are divided into: whole-microbial or whole-virion
• chemical vaccines, consisting of microorganisms, respectively bacteria or viruses, which retain their integrity during the manufacturing process; from the metabolic products of a microorganism (a classic example is toxoids
• ) or its integral components, the so-called. submicrobial or subvirion vaccines; genetically engineered vaccines
• , containing expression products of individual microorganism genes produced in special cellular systems; chimeric or vector vaccines
• , in which the gene that controls the synthesis of a protective protein is built into a harmless microorganism in the expectation that the synthesis of this protein will occur in the vaccinated body and, finally;, where a chemical analogue of a protective protein obtained by direct chemical synthesis is used as an immunogen.

In turn, among whole-microbial (whole-virion) vaccines there are inactivated or killed, And alive attenuated. The effectiveness of live vaccines is ultimately determined by the ability of the attenuated microorganism to multiply in the body of the vaccinated person, reproducing the immunologically active components directly in his tissues. When using killed vaccines, the immunizing effect depends on the amount of immunogen administered as part of the drug, therefore, in order to create more complete immunogenic stimuli, it is necessary to resort to the concentration and purification of microbial cells or viral particles.

Live vaccines

Attenuated - weakened in its virulence (infectious aggressiveness), i.e. artificially modified by man or “donated” by nature, which changed their properties in natural conditions, an example of which is the vaccinia vaccine. The active factor of such vaccines is the altered genetic characteristics of microorganisms, which at the same time ensure that the child suffers a “minor disease” with the subsequent acquisition of specific anti-infectious immunity. An example would be vaccines against polio, measles, mumps, rubella or tuberculosis.

Positive sides: according to the mechanism of action on the body, they resemble the “wild” strain, can take root in the body and maintain immunity for a long time (for measles vaccine, vaccination at 12 months and revaccination at 6 years), displacing the “wild” strain. Small doses are used for vaccination (usually a single dose) and therefore vaccination is easy to carry out organizationally. The latter allows us to recommend this type of vaccine for further use.

Negative sides: live corpuscular vaccine - contains 99% ballast and therefore is usually quite reactogenic, in addition, it can cause mutations in body cells (chromosomal aberrations), which is especially dangerous in relation to germ cells. Live vaccines contain contaminating viruses (contaminants), this is especially dangerous in relation to simian AIDS and oncoviruses. Unfortunately, live vaccines are difficult to dose and biocontrol, are easily sensitive to high temperatures and require strict adherence to the cold chain.

Although live vaccines require special storage conditions, they produce fairly effective cellular and humoral immunity and usually require only one booster dose. Most live vaccines are administered parenterally (with the exception of polio vaccine).

Against the background of the advantages of live vaccines, there is one warning, namely: the possibility of reversion of virulent forms, which can cause illness in the vaccinated person. For this reason, live vaccines must be thoroughly tested. Patients with immunodeficiencies (receiving immunosuppressive therapy, AIDS and tumors) should not receive such vaccines.

An example of live vaccines are vaccines for the prevention rubella (Rudivax), measles (Ruvax), poliomyelitis (Polio Sabin Vero), tuberculosis, mumps (Imovax Oreyon).

Inactivated (killed) vaccines

Inactivated vaccines are produced by exposing microorganisms chemically or by heating. Such vaccines are quite stable and safe, since they cannot cause a reversion of virulence. They often do not require cold storage, which is convenient for practical use. However, these vaccines also have a number of disadvantages, in particular, they stimulate a weaker immune response and require multiple doses.

They contain either a killed whole microorganism (eg whole cell pertussis vaccine, inactivated rabies vaccine, hepatitis A vaccine) or components of the cell wall or other parts of the pathogen, such as in acellular pertussis vaccine, haemophilus influenzae conjugate vaccine or against meningococcal infection. They are killed by physical (temperature, radiation, ultraviolet light) or chemical (alcohol, formaldehyde) methods. Such vaccines are reactogenic and rarely used (whooping cough, hepatitis A).

Inactivated vaccines are also corpuscular. When analyzing the properties of corpuscular vaccines, one should also highlight both their positive and negative qualities. Positive sides: Killed corpuscular vaccines are easier to dose, better to clean, have a longer shelf life and are less sensitive to temperature fluctuations. Negative sides: corpuscular vaccine - contains 99% ballast and therefore reactogenic, in addition, contains an agent used to kill microbial cells (phenol). Another disadvantage of an inactivated vaccine is that the microbial strain does not take root, therefore the vaccine is weak and vaccination is carried out in 2 or 3 doses, requiring frequent revaccinations (DPT), which is more difficult to organize compared to live vaccines. Inactivated vaccines are produced both in dry (lyophilized) and liquid form. Many microorganisms that cause diseases in humans are dangerous because they secrete exotoxins, which are the main pathogenetic factors of the disease (for example, diphtheria, tetanus). Toxoids used as vaccines induce a specific immune response. To obtain vaccines, toxins are most often neutralized using formaldehyde.

Associated vaccines

Vaccines of various types containing several components (DTP).

Corpuscular vaccines

They are bacteria or viruses inactivated by chemical (formalin, alcohol, phenol) or physical (heat, ultraviolet irradiation) effects. Examples of corpuscular vaccines are: pertussis (as a component of DPT and Tetracoc), rabies, leptospirosis, whole virion influenza, vaccines against encephalitis, against hepatitis A (Avaxim), inactivated polio vaccine (Imovax Polio, or as a component of the Tetracoc vaccine).

Chemical vaccines

Chemical vaccines are created from antigenic components extracted from a microbial cell. Those antigens are isolated that determine the immunogenic characteristics of the microorganism. These vaccines include: polysaccharide vaccines (Meningo A + C, Act - Hib, Pneumo 23, Typhim Vi), acellular pertussis vaccines.

Biosynthetic vaccines

In the 1980s, a new direction was born, which is now successfully developing - the development of biosynthetic vaccines - vaccines of the future.

Biosynthetic vaccines are vaccines obtained using genetic engineering methods and are artificially created antigenic determinants of microorganisms. An example is a recombinant vaccine against viral hepatitis B, a vaccine against rotavirus infection. To obtain them, yeast cells are used in culture, into which an excised gene is inserted, encoding the production of the protein necessary to obtain the vaccine, which is then isolated in its pure form.

At the present stage of development of immunology as a fundamental medical and biological science, the need to create fundamentally new approaches to the design of vaccines based on knowledge of the antigenic structure of the pathogen and the body’s immune response to the pathogen and its components has become obvious.

Biosynthetic vaccines are peptide fragments synthesized from amino acids that correspond to the amino acid sequence of those viral (bacterial) protein structures that are recognized by the immune system and cause an immune response. An important advantage of synthetic vaccines compared to traditional ones is that they do not contain bacteria, viruses, or their waste products and cause an immune response of narrow specificity. In addition, the difficulties of growing viruses, storage and the possibility of replication in the body of the vaccinated person are eliminated in the case of using live vaccines. When creating this type of vaccine, several different peptides can be attached to the carrier, and the most immunogenic ones can be selected for complexation with the carrier. At the same time, synthetic vaccines are less effective compared to traditional ones, since many parts of the viruses exhibit variability in terms of immunogenicity and provide less immunogenicity than the native virus. However, the use of one or two immunogenic proteins instead of the whole pathogen ensures the formation of immunity with a significant reduction in the reactogenicity of the vaccine and its side effects.

Vector (recombinant) vaccines

Vaccines obtained using genetic engineering methods. The essence of the method: the genes of a virulent microorganism responsible for the synthesis of protective antigens are inserted into the genome of a harmless microorganism, which, when cultivated, produces and accumulates the corresponding antigen. An example is a recombinant vaccine against viral hepatitis B, a vaccine against rotavirus infection. Finally, there are positive results from using the so-called. vector vaccines, when the surface proteins of two viruses are applied to the carrier - a live recombinant vaccinia virus (vector): glycoprotein D of the herpes simplex virus and hemagglutinin of the influenza A virus. Unlimited replication of the vector occurs and an adequate immune response develops against viral infection of both types.

Recombinant vaccines - These vaccines use recombinant technology by inserting the genetic material of a microorganism into yeast cells that produce the antigen. After cultivating the yeast, the desired antigen is isolated from it, purified, and a vaccine is prepared. An example of such vaccines is the hepatitis B vaccine (Euvax B).

Ribosomal vaccines

To obtain this type of vaccine, ribosomes found in every cell are used. Ribosomes are organelles that produce protein using a matrix - mRNA. The isolated ribosomes with the matrix in their pure form represent the vaccine. Examples include bronchial and dysentery vaccines (e.g. IRS - 19, Broncho-munal, Ribomunil).

Vaccination effectiveness

Post-vaccination immunity is immunity that develops after administration of a vaccine. Vaccination is not always effective. Vaccines lose their quality if stored improperly. But even if the storage conditions are met, there is always a possibility that the immune system will not be stimulated.

The development of post-vaccination immunity is influenced by the following factors:

1. Dependent on the vaccine itself:

Purity of the drug;
- antigen lifetime;
- dose;
- presence of protective antigens;
- frequency of administration.

2. Dependent on the body:

State of individual immune reactivity;
- age;
- presence of immunodeficiency;
- the state of the body as a whole;
- genetic predisposition.

3. Dependent on the external environment

Nutrition;
- working and living conditions;
- climate;
- physical and chemical environmental factors.

The ideal vaccine

The development and production of modern vaccines is carried out in accordance with high requirements for their quality, first of all, harmlessness to those vaccinated. Typically, such requirements are based on the recommendations of the World Health Organization, which attracts the most authoritative experts from around the world to compile them. An “ideal” vaccine would be one that has the following qualities:

1. complete harmlessness for vaccinated people, and in the case of live vaccines, for persons to whom the vaccine microorganism reaches as a result of contacts with vaccinated people;

2. the ability to induce lasting immunity after a minimum number of administrations (no more than three);

3. the possibility of introduction into the body in a way that excludes parenteral manipulation, for example, application to mucous membranes;

4. sufficient stability to prevent deterioration of the properties of the vaccine during transportation and storage in the conditions of a vaccination point;

5. at a reasonable price, which would not interfere with the mass use of the vaccine.