Characteristics and classification of vaccines

Vaccines (defined in this article) are immunological agents used as active immunoprophylaxis (otherwise - to form an active resistant immunity of the organism to this particular pathogen). According to the conclusion of the WHO, vaccination is the optimal method of preventing infectious pathologies. Due to the high efficiency, simplicity of the method, the possibility of wide coverage of the vaccinated population for mass prevention of pathologies, immunoprophylaxis in many countries is classified as a state priority.

Vaccination

Vaccination is a special preventive measure aimed at protecting a child or an adult from some pathologies completely or significantly reducing their appearance in the occurrence.

This effect is achieved by "learning" immunity. With the introduction of the drug, the body (more precisely, its immune system) fights against an artificially introduced infection and "remembers" it. With re-infection, immunity activates much faster and completely destroys foreign agents.

The list of vaccination activities includes:

• Selection of subjects to be vaccinated;
• Choice of preparation;
• Formation of a vaccine use regimen;
• Performance monitoring;
• Therapy (if necessary) of possible complications and pathological reactions.

Methods of vaccination

• Intracutaneous. An example is BCG. The introduction of live vaccine is produced in the shoulder (its outer third). A similar method is also used for the prevention of tularemia, plague, brucellosis, Siberian ulcer, fever Ku.
• Oral. It is used for the prevention of poliomyelitis and rabies. At the development stages oral means for influenza, measles, typhoid fever, meningococcal infection.
• Subcutaneous. With this method, the non-adsorbed preparation is injected into the subscapular or brachial (outer surface at the border of the middle and upper thirds of the shoulder) region. Advantages: low allergenicity, ease of administration, immunity stability (both local and general).
• Aerosol. It is used as an emergency immunization. Highly effective are aerosol products against brucellosis, influenza, tularemia, diphtheria, Siberian ulcers, whooping cough, plague, rubella, gas gangrene, tuberculosis, tetanus, typhoid fever, botulism, dysentery, mumps B.
• Intramuscular. Produced in the muscles of the thigh (in the upper anterior part of the quadriceps femoris muscle). For example, DTP.

Modern classification of vaccines

There are several divisions of vaccine preparations.

1. Classification of funds in accordance with the generation:

• 1 generation (corpuscular vaccines). In turn, they are divided into attenuated (weakened living) and inactivated (killed) means;
• 2nd generation: subunit (chemical) and neutralized exotoxins (toxoids);
• 3 generation is represented by recombinant hepatitis B vaccines and recombinant rabies vaccines;
• 4 generation (not yet included in practice), is represented by plasmid DNA, synthetic peptides, plant vaccines, vaccines that contain MHC products and anti-idiotypic drugs.

2. Classification of vaccines (microbiology also divides them into several classes) by origin. By origin, vaccines are divided into:

• Live that is made of living, but weakened microorganisms;
• Killed, created on the basis of microorganisms inactivated in various ways;
• Vaccines of chemical origin (based on highly purified antigens);
• Vaccines that are created with the help of biotechnological techniques, in turn are divided into:

- synthetic vaccines based on oligosaccharides and oligopeptides;

- DNA vaccines;

- genetically engineered vaccines, created on the basis of products formed as a result of the synthesis of recombinant systems.

3. In accordance with the ingredients of Ar, there is the following classification of vaccines (that is, as Ar in vaccines may be present):

• Whole microbial cells (inactivated or alive);
• Separate components of microbial bodies (more often protective Ar);
• Microbial toxins;
• The synthetically produced Ag microbes;
• Ag, which are obtained with the help of genetic engineering techniques.

Depending on the ability to develop insensitivity to several or one agent:

• Monovaccines;
• Polivakciny.

Classification of vaccines in accordance with a set of Ag:

• Component;
• Corpuscular.

Live vaccines

To produce such vaccines, weakened strains of infectious agents are used. Similar vaccines have immunogenic properties, however, the appearance of symptoms of the disease during immunization, as a rule, does not cause.

As a result of the penetration of live vaccine into the body, stable cellular, secretory, humoral immunity is formed.

Advantages and disadvantages

The advantages of living vaccine (classification, application are discussed in this article):

• A minimum dosage is required;
• The possibility of a variety of vaccination methods;
• Rapid development of immunity;
• high efficiency;
• low price;
• Immunogenicity is maximally natural;
• In the composition there are no preservatives;
• Under the influence of such vaccines, all types of immunity are activated.

Negative sides:

• If the patient has a weakened immunity with the introduction of a live vaccine, the development of the disease is possible;
• Vaccines of this type are extremely sensitive to temperature changes, and therefore when a "spoiled" living vaccine is introduced, negative reactions develop or the vaccine completely loses its properties;
• The inability to combine such vaccines with other vaccine preparations, due to the development of adverse reactions or loss of therapeutic effectiveness.

Classification of live vaccines

There are the following types of live vaccines:

• Attenuated (attenuated) vaccine preparations. They are produced from strains that have reduced pathogenicity, but pronounced immunogenicity. When a vaccine strain is introduced into the body, the semblance of an infectious process develops: infectious agents multiply, thereby causing the formation of immune reactions. Among such vaccines, preparations for the prevention of typhoid fever, Siberian ulcers, Ku-fever and brucellosis are most known. But most of the live vaccines are antiviral drugs against adenovirus infections, yellow fever, mumps, Sabin vaccine (against poliomyelitis), rubella, measles, influenza;
• Vaccines divergent. They are made on the basis of related causative agents of infectious pathologies of strains. Their antigens provoke the appearance of an immune response, cross-directed to the antigens of the pathogen. An example of such vaccines is a vaccine against smallpox, which is made on the basis of cow and BCG pox virus, on the basis of mycobacteria that cause bovine tuberculosis.

Vaccines for influenza

Vaccines are used as the most effective prevention of influenza. They are biological agents that ensure the emergence of short-term resistance to influenza viruses.

Indications for such vaccinations are:

• Age 60 years and older;
• Bronchopulmonary chronic or cardiovascular pathologies;
• Pregnancy (2-3 trimesters);
• Staff of dispensaries and hospitals;
• Persons permanently staying in closed collectives (prisons, hostels, nursing homes, etc.);
• Patients who are on inpatient or outpatient care that have hemoglobinopathies, immunosuppression, liver pathology, kidney and metabolic disorders.

Varieties

The classification of influenza vaccines includes the following groups:

1. Live vaccines;
2. Vaccines inactivated:

• Vaccines are whole-virion. Include undisturbed highly purified inactivated virions;
• Splitted (split-vaccines). For example: "Fluariks", "Begrivak", "Vaksgripp". Created on the basis of destroyed influenza virions (all proteins of the virus);

• Subunit vaccines (Agrippal, Grippol, Influvak) have two viral surface proteins, neuraminidase and hemagglutinin, which provide the induction of an immune response in influenza. Other proteins of the virion, as well as the chicken embryo, are absent, since they are eliminated during purification.