Characterization and classification of vaccines

Vaccines (the definition, the classification of which is considered in this article) are immunological agents used as active immunoprophylaxis (otherwise - for the formation of an active persistent immunity of an organism to a given specific pathogen). According to the WHO, vaccination is the best method for the prevention of infectious pathologies. Due to the high efficiency, simplicity of the method, the possibility of wide coverage of the vaccinated population for the 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 certain pathologies completely or significantly reducing their appearance when they occur.

A similar effect is achieved through the "training" of immunity. With the introduction of the drug, the body (more precisely, its immune system) fights the artificially introduced infection and "remembers" it. With re-infection, immunity is activated much faster and completely destroys foreign agents.

The list of ongoing vaccination activities includes:

• selection of persons to be vaccinated;
• drug selection;
• formation of a vaccine administration schedule;
• performance control;
• therapy (if necessary) of possible complications and pathological reactions.

Vaccination methods

• Intradermal. An example is BCG. The introduction of a live vaccine is produced in the shoulder (its outer third). A similar method is also used to prevent tularemia, plague, brucellosis, anthrax, and Q fever.
• Oral It is used to prevent poliomyelitis and rabies. At the stages of development, oral agents for influenza, measles, typhoid fever, meningococcal infection.
• Subcutaneous. With this method, the non-adsorbed preparation is introduced into the subscapular or brachial (outer surface at the border of the middle and upper third of the shoulder) region. Advantages: low allergenicity, ease of administration, immunity (both local and general).
• Aerosol. It is used as emergency immunization. Aerosols against brucellosis, influenza, tularemia, diphtheria, anthrax, pertussis, plague, rubella, gas gangrene, tuberculosis, tetanus, typhoid fever, botulism, dysentery, and mumps B are highly effective.
• Intramuscular. It is produced in the muscles of the thigh (in the upper anteroposterior part of the quadriceps femoris). For example, DTP.

Modern vaccine classification

There are several vaccine units.

1. Classification of funds in accordance with the generation:

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

2. Classification of vaccines (microbiology also divides them into several classes) by origin. The origin of the vaccine is divided into:

• living that are made from living but weakened microorganisms;
• slaughtered, created on the basis of microorganisms inactivated in various ways;
• vaccines of chemical origin (based on highly purified antigens);
• vaccines that are created using biotechnological techniques, in turn, are divided into:

- synthetic vaccines based on oligosaccharides and oligopeptides;

- DNA vaccines;

- Genetic engineering vaccines based on products resulting from the synthesis of recombinant systems.

3. In accordance with the components of the Ag preparations, the following classification of vaccines exists (that is, they may be present as vaccines in the vaccines):

• whole microbial cells (inactivated or living);
• individual components of microbial bodies (often protective Ag);
• microbial toxins;
• Synthetically created Ag microbes;
• Ag, that obtained using genetic engineering techniques.

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

• monovaccines;
• multivaccines.

Vaccine classification according to Ag kit:

• component
• corpuscular.

Live vaccines

For the manufacture of such vaccines using attenuated strains of infectious agents. Such vaccines have immunogenic properties, but, as a rule, they do not cause symptoms of the disease during immunization.

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

Advantages and disadvantages

The benefits of a live vaccine (classification, use discussed in this article):

• minimum dosage required;
• the possibility of various methods of vaccination;
• rapid development of immunity;
• high efficiency;
• low price;
• immunogenicity is as natural as possible;
• there are no preservatives in the composition;
• under the influence of such vaccines, all types of immunity are activated.

Negative sides:

• if the patient has 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 extremes, and therefore, when a "spoiled" live 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 efficacy.

Classification of live vaccines

The following types of live vaccines are distinguished:

• Attenuated (attenuated) vaccine preparations. They are produced from strains that have reduced pathogenicity, but pronounced immunogenicity. With the introduction of a vaccine strain, the body develops a semblance of an infectious process: infectious agents multiply, thereby causing the formation of immune reactions. Among these vaccines, drugs for the prevention of typhoid fever, anthrax, Q fever and brucellosis are the most well-known. But still, the bulk of live vaccines are antiviral drugs for adenovirus infections, yellow fever, mumps, the Sabin vaccine (against polio), rubella, measles, and flu;
• Divergent vaccines. They are made on the basis of related pathogens of infectious pathologies of strains. Their antigens provoke the appearance of an immune response cross-directed to the pathogen antigens. An example of such vaccines is a vaccine against natural smallpox, which is made on the basis of the smallpox virus of cow and BCG, on the basis of mycobacteria that cause bovine tuberculosis.

Flu vaccines

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

Indications for such vaccinations are:

• age 60 years and older;
• chronic bronchopulmonary or cardiovascular pathology;
• pregnancy (2-3 trimesters);
• ambulatory and hospital personnel;
• persons permanently residing in closed collectives (prisons, dormitories, nursing homes, and so on);
• patients who are on inpatient or outpatient treatment that have hemoglabinopathies, immunosuppression, liver, kidney and metabolic disorders.

Varieties

The classification of influenza vaccines includes the following groups:

1. Live vaccines;
2. Inactivated vaccines:

• whole virion vaccines. Include intact highly purified inactivated virions;
• split (split vaccines). For example: Fluarix, Begrivak, Vaksigripp. Created on the basis of destroyed influenza virions (all proteins of the virus);

• subunit vaccines (Agrippal, Grippol, Influvac) have two viral surface proteins, neuraminidase and hemagglutinin, which induce an immune response in case of influenza. Other proteins of the virion, as well as the chicken embryo are absent, as they are eliminated during cleaning.