Lecture: Vaccines, requirements for vaccines. Types of vaccines, characteristics, methods of preparation

Date: 20.06.2020

The fear of vaccines is largely due to outdated ideas about vaccines. Of course, the general principles of their action have remained unchanged since the time of Edward Jenner, who in 1796 was the first to use smallpox vaccination. But medicine has come a long way since then.

So-called "live" vaccines, which use a weakened virus, are still used today. But this is only one of the varieties of remedies designed to prevent dangerous diseases. And every year - in particular, thanks to the achievements of genetic engineering - the arsenal is replenished with new types and even types of vaccines.

Live vaccines

They require special storage conditions, but provide stable immunity to the disease after one, as a rule, vaccination. For the most part, they are administered parenterally, that is, by injection; The exception is the polio vaccine. Despite the benefits of live vaccines, their use is associated with some risks. There is always a chance that a strain of the virus will be virulent enough to cause the disease that the vaccine was supposed to protect against. Therefore, live vaccines are not used in people with immunodeficiency (for example, HIV carriers, cancer patients).

Inactivated vaccines

For their manufacture, microorganisms are used "killed" by heating or by chemical action. There is no chance of resuming virulence, and therefore such vaccines are safer than “live” ones. But, of course, there is a downside - a weaker immune response. That is, repeated vaccinations are required to develop stable immunity.

Anatoxins

Many microorganisms in the process of life emit substances dangerous to humans. They become the direct cause of the disease, for example, diphtheria or tetanus. Containing toxoid (weakened toxin) vaccines, in the language of physicians, "induce a specific immune response." In other words, they are designed to “teach” the body to independently produce antitoxins that neutralize harmful substances.

conjugate vaccines

Some bacteria have antigens that are poorly recognized by the immature immune system of infants. In particular, these are bacteria that cause such dangerous diseases as meningitis or pneumonia. Conjugate vaccines are designed to get around this problem. They use microorganisms that are well recognized by the child's immune system and contain antigens similar to those of the pathogen, for example, meningitis.

Subunit Vaccines

Effective and safe - they use only fragments of the antigen of a pathogenic microorganism, sufficient to ensure an adequate immune response of the body. May contain particles of the microbe itself (vaccines against Streptococcus pneumoniae and against meningococcus type A). Another option is recombinant subunit vaccines created using genetic engineering technology. For example, the hepatitis B vaccine is made by injecting some of the virus's genetic material into baker's yeast cells.

Recombinant vector vaccines

The genetic material of the microorganism that causes the disease, to which it is necessary to create protective immunity, is introduced into a weakened virus or bacterium. For example, human-safe vaccinia virus is used to create recombinant vector vaccines against HIV infection. Attenuated salmonella bacteria are used as carriers of hepatitis B virus particles.

They are a suspension of vaccine strains of microorganisms (bacteria, viruses, rickettsia) grown on various nutrient media. Usually, strains of microorganisms with weakened virulence or devoid of virulence properties, but completely retained immunogenic properties, are used for vaccination. These vaccines are produced on the basis of apathogenic pathogens, attenuated (weakened) in artificial or natural conditions. Attenuated strains of viruses and bacteria are obtained by inactivation of the gene responsible for the formation of the virulence factor, or by mutations in genes that nonspecifically reduce this virulence.

In recent years, recombinant DNA technology has been used to obtain attenuated strains of some viruses. Large DNA-containing viruses, such as the vaccinia virus, can serve as vectors for cloning foreign genes. Such viruses retain their infectivity, and the cells infected by them begin to secrete proteins encoded by the transfected genes.

Due to the genetically fixed loss of pathogenic properties and the loss of the ability to cause an infectious disease, vaccine strains retain the ability to multiply at the injection site, and later in regional lymph nodes and internal organs. Vaccine infection lasts for several weeks, is not accompanied by a pronounced clinical picture of the disease and leads to the formation of immunity to pathogenic strains of microorganisms.

Live attenuated vaccines are prepared from attenuated microorganisms. Weakening of microorganisms is also achieved by growing crops in adverse conditions. Many vaccines are produced in dry form in order to increase the shelf life.

Live vaccines have significant advantages over killed ones, due to the fact that they completely preserve the antigenic set of the pathogen and provide a longer state of immunity. However, given the fact that the active principle of live vaccines are live microorganisms, it is necessary to strictly comply with the requirements that ensure the preservation of the viability of microorganisms and the specific activity of vaccines.

There are no preservatives in live vaccines; when working with them, it is necessary to strictly observe the rules of asepsis and antisepsis.

Live vaccines have a long shelf life (1 year or more), they are stored at a temperature of 2-10 C.

5-6 days before the introduction of live vaccines and 15-20 days after vaccination, antibiotics, sulfanilamide, nitrofuran preparations and immunoglobulins should not be used for treatment, as they reduce the intensity and duration of immunity.

Vaccines create active immunity in 7-21 days, which lasts up to 12 months on average.

Killed (inactivated) vaccines

To inactivate microorganisms, heating, treatment with formalin, acetone, phenol, ultraviolet rays, ultrasound, and alcohol are used. Such vaccines are not dangerous, they are less effective than live ones, but when they are repeatedly administered, they create a fairly strong immunity.

In the production of inactivated vaccines, it is necessary to strictly control the process of inactivation and at the same time preserve the set of antigens in the killed cultures.

Killed vaccines do not contain live microorganisms. The high efficiency of killed vaccines is associated with the preservation of a set of antigens in inactivated cultures of microorganisms that provide an immune response.

For the high efficiency of inactivated vaccines, the selection of industrial strains is of great importance. For the manufacture of polyvalent vaccines, it is best to use strains of microorganisms with a wide range of antigens, taking into account the immunological relationship of various serological groups and variants of microorganisms.

The spectrum of pathogens used for the preparation of inactivated vaccines is very diverse, but the most widespread are bacterial (vaccine against necrobacteriosis) and viral (anti-rabies inactivated dry culture vaccine against rabies from the Schelkovo-51 strain.

Inactivated vaccines should be stored at 2-8°C.

Chemical vaccines

They consist of antigenic complexes of microbial cells connected with adjuvants. Adjuvants are used to enlarge antigenic particles, as well as to increase the immunogenic activity of vaccines. Adjuvants include aluminum hydroxide, alum, organic or mineral oils.

The emulsified or adsorbed antigen becomes more concentrated. When introduced into the body, it is deposited and comes from the injection site to organs and tissues in small doses. Slow resorption of the antigen prolongs the immune effect of the vaccine and significantly reduces its toxic and allergic properties.

Chemical vaccines include deposited vaccines against swine erysipelas and swine streptococcosis (serogroups C and R).

Associated vaccines

They consist of a mixture of cultures of microorganisms that cause various infectious diseases, which do not inhibit the immune properties of each other. After the introduction of such vaccines, immunity is formed in the body against several diseases at the same time.

Anatoxins

These are drugs containing toxins, devoid of toxic properties, but retained antigenicity. They are used to induce immune responses aimed at neutralizing toxins.

Anatoxins are produced from exotoxins of various types of microorganisms. To do this, toxins are neutralized with formalin and kept in a thermostat at a temperature of 38-40 ° C for several days. Toxoids, in essence, are analogues of inactivated vaccines. They are cleaned of ballast substances, adsorbed and concentrated on aluminum hydroxide. Adsorbents are introduced into the toxoid to enhance adjuvant properties.

Anatoxins create antitoxic immunity, which persists for a long time.

Recombinant vaccines

Using genetic engineering methods, it is possible to create artificial genetic structures in the form of recombinant (hybrid) DNA molecules. A recombinant DNA molecule with new genetic information is introduced into the recipient's cell using carriers of genetic information (viruses, plasmids), which are called vectors.

Obtaining recombinant vaccines includes several stages:

cloning of genes that provide the synthesis of the necessary antigens;
introduction of cloned genes into a vector (viruses, plasmids);
introduction of vectors into producer cells (viruses, bacteria, fungi);
cultivation of cells in vitro;
antigen isolation and purification or use of producer cells as vaccines.

The finished product must be tested against a natural reference drug or one of the first series of genetically engineered drug that has passed preclinical and clinical trials.

BG Orlyankin (1998) reports that a new direction in the development of genetically engineered vaccines has been created, based on the introduction of plasmid DNA (vector) with an integrated protective protein gene directly into the body. In it, plasmid DNA does not multiply, does not integrate into chromosomes and does not cause an antibody formation reaction. Plasmid DNA with an integrated protective protein genome induces a complete cellular and humoral immune response.

On the basis of a single plasmid vector, various DNA vaccines can be constructed by changing only the gene encoding the protective protein. DNA vaccines have the safety of inactivated vaccines and the efficacy of live ones. Currently, more than 20 recombinant vaccines have been designed against various human diseases: vaccine against rabies, Aujeszky's disease, infectious rhinotracheitis, viral diarrhea, respiratory syncytial infection, influenza A, hepatitis B and C, lymphocytic choriomeningitis, human T-cell leukemia, herpesvirus infection person and others.

DNA vaccines have a number of advantages over other vaccines.

When developing such vaccines, it is possible to quickly obtain a recombinant plasmid carrying the gene encoding the necessary pathogen protein, in contrast to the long and expensive process of obtaining attenuated strains of the pathogen or transgenic animals.
Manufacturability and low cost of cultivation of the obtained plasmids in E. coli cells and its further purification.
The protein expressed in the cells of the vaccinated organism has a conformation as close as possible to the native one and has a high antigenic activity, which is not always achieved when using subunit vaccines.
Elimination of the vector plasmid in the body of the vaccinated occurs in a short period of time.
With DNA vaccination against particularly dangerous infections, the likelihood of disease as a result of immunization is completely absent.
Prolonged immunity is possible.

All of the above makes it possible to call DNA vaccines the vaccines of the 21st century.

However, the idea of complete control of infections through vaccines was held until the late 1980s, when it was shaken by the AIDS pandemic.

DNA immunization is also not a universal panacea. Since the second half of the 20th century, infectious agents that cannot be controlled by immunoprophylaxis have become increasingly important. The persistence of these microorganisms is accompanied by the phenomenon of antibody-dependent increase in infection or integration of the provirus into the genome of the macroorganism. Specific prevention can be based on inhibition of pathogen penetration into sensitive cells by blocking recognition receptors on their surface (viral interference, water-soluble compounds that bind receptors) or by inhibiting their intracellular reproduction (oligonucleotide and antisense inhibition of pathogen genes, destruction of infected cells by a specific cytotoxin, etc.). ).

The problem of provirus integration can be solved by cloning transgenic animals, for example, by obtaining lines that do not contain provirus. Therefore, DNA vaccines should be developed against pathogens whose persistence is not accompanied by an antibody-dependent increase in infection or persistence of the provirus in the host genome.

Seroprophylaxis and serotherapy

Serums (Serum) form passive immunity in the body, which lasts 2-3 weeks, and is used to treat patients or prevent diseases in a threatened zone.

Immune sera contain antibodies, so they are most often used for therapeutic purposes at the onset of the disease in order to achieve the greatest therapeutic effect. Serums can contain antibodies against microorganisms and toxins, so they are divided into antimicrobial and antitoxic.

Serums are obtained at biofactories and biocombines by two-stage hyperimmunization of immunoserum producers. Hyperimmunization is carried out with increasing doses of antigens (vaccines) according to a certain scheme. At the first stage, the vaccine is administered (I-2 times), and then, according to the scheme in increasing doses, a virulent culture of the production strain of microorganisms is administered for a long time.

Thus, depending on the type of immunizing antigen, antibacterial, antiviral and antitoxic sera are distinguished.

It is known that antibodies neutralize microorganisms, toxins or viruses, mainly before they enter the target cells. Therefore, in diseases where the pathogen is localized intracellularly (tuberculosis, brucellosis, chlamydia, etc.), it has not yet been possible to develop effective methods of serotherapy.

Serum therapeutic and prophylactic drugs are used mainly for emergency immunoprophylaxis or the elimination of certain forms of immunodeficiency.

Antitoxic sera are obtained by immunizing large animals with increasing doses of antitoxins, and then toxins. The resulting sera are purified and concentrated, freed from ballast proteins, and standardized for activity.

Antibacterial and antiviral drugs are obtained by hyperimmunization of horses with appropriate killed vaccines or antigens.

The disadvantage of the action of serum preparations is the short duration of the formed passive immunity.

Heterogeneous sera create immunity for 1-2 weeks, globulins homologous to them - for 3-4 weeks.

Methods and procedure for administering vaccines

There are parenteral and enteral methods of introducing vaccines and sera into the body.

With the parenteral method, drugs are administered subcutaneously, intradermally and intramuscularly, which allows you to bypass the digestive tract.

One of the types of parenteral administration of biological products is aerosol (respiratory), when vaccines or sera are administered directly into the respiratory tract by inhalation.

The enteral method involves the introduction of biological products through the mouth with food or water. At the same time, the consumption of vaccines increases due to their destruction by the mechanisms of the digestive system and the gastrointestinal barrier.

After the introduction of live vaccines, immunity is formed in 7-10 days and persists for a year or more, and with the introduction of inactivated vaccines, the formation of immunity ends by the 10-14th day and its tension persists for 6 months.

Table of contents of the subject "Immunodeficiencies. Vaccines. Serums. Immunoglobulins.":

Vaccines. Types of vaccine antigens. classification of vaccines. Types of vaccines. live vaccines. Weakened (attenuated) vaccines. divergent vaccines.

Vaccines- immunobiological preparations intended for active immunoprophylaxis, that is, to create an active specific immunity of the body to a specific pathogen. Vaccination recognized by WHO as an ideal method for the prevention of human infectious diseases. High efficiency, simplicity, and the possibility of wide coverage of vaccinated persons in order to prevent the disease on a mass scale have brought active immunoprophylaxis into the category of state priorities in most countries of the world. A set of measures for vaccination includes the selection of persons to be vaccinated, the choice of a vaccine preparation and the determination of the scheme for its use, as well as (if necessary) monitoring the effectiveness, stopping possible pathological reactions and complications. As antigen in vaccine preparations are:

Whole microbial bodies (live or killed);
individual antigens of microorganisms (most often protective antigens);
microorganism toxins;
artificially created Ag microorganisms;
Ag obtained by genetic engineering.

Most vaccines divided into living, inactivated (killed, non-living), molecular (toxoids), genetically engineered and chemical; by the presence of a complete or incomplete set of antigens - into corpuscular and component, and by the ability to develop immunity to one or more pathogens - into mono- and associated.

Live vaccines

Live vaccines- preparations from attenuated (weakened) or genetically modified pathogenic microorganisms, as well as closely related microbes capable of inducing immunity to a pathogenic species (in the latter case, we are talking about the so-called divergent vaccines). Since everything live vaccines contain microbial bodies, they are classified as corpuscular vaccine preparations.

Immunization with a live vaccine leads to the development of the vaccination process, which occurs in the majority of those vaccinated without visible clinical manifestations. The main advantage of live vaccines is a completely preserved set of antigens of the pathogen, which ensures the development of long-term immunity even after a single immunization. Live vaccines also have a number of disadvantages. The most characteristic is the risk of developing a manifest infection as a result of a decrease in the attenuation of the vaccine strain. Similar phenomena are more typical for antiviral vaccines (for example, live polio vaccine can rarely cause poliomyelitis up to the development of spinal cord injury and paralysis).

Attenuated (attenuated) vaccines

Weakened ( attenuated) vaccines are made from microorganisms with reduced pathogenicity, but pronounced immunogenicity. The introduction of a vaccine strain into the body imitates the infectious process: the microorganism multiplies, causing the development of immune responses. The best known vaccines are for the prevention of anthrax, brucellosis, Q fever, and typhoid fever. However, most live vaccines- antiviral. The best known are the yellow fever vaccine, Sabin's polio vaccine, vaccines against influenza, measles, rubella, mumps, and adenovirus infections.

Divergent vaccines

As vaccine strains use microorganisms that are closely related to pathogens of infectious diseases. Ag of such microorganisms induce an immune response that is cross-directed to Ag of the pathogen. The best known and longest used vaccine is against smallpox (from the vaccinia virus) and BCG for the prevention of tuberculosis (from Mycobacterium bovine tuberculosis).

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In the arsenal of modern immunoprophylaxis, there are several dozen immunoprophylactic agents.

There are currently two types of vaccines:

traditional (first and second generation) and
third-generation vaccines designed on the basis of biotechnology methods.

First and second generation vaccines

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Among first and second generation vaccines distinguish:

live,
inactivated (killed) and
chemical vaccines.

Live vaccines

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To create live vaccines, microorganisms (bacteria, viruses, rickettsiae) with weakened virulence that have arisen naturally or artificially in the process of strain selection are used. The effectiveness of a live vaccine was first shown by the English scientist E. Jenner (1798), who proposed for immunization against smallpox a vaccine containing a low-virulence vaccinia pathogen for humans, from the Latin word vasca - cow and the name "vaccine" came from. In 1885, L. Pasteur proposed a live vaccine against rabies from a weakened (attenuated) vaccine strain. The French researchers A. Calmette and C. Guerin, in order to weaken the virulence, cultivated for a long time on an unfavorable medium for the microbe, mycobacterium tuberculosis of the bovine type, which are used to obtain a live BCG vaccine.

In Russia, both domestic and foreign live attenuated vaccines are used. These include vaccines against poliomyelitis, measles, mumps, rubella, and tuberculosis, which are included in the preventive vaccination calendar.

Vaccines against tularemia, brucellosis, anthrax, plague, yellow fever, influenza are also used. Live vaccines create intense and long-lasting immunity.

Inactivated vaccines

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Inactivated (killed) vaccines are preparations prepared using industrial strains of pathogens of the relevant infections and preserving the corpuscular structure of the microorganism. (The strains have full antigenic properties.) There are various methods of inactivation, the main requirements for which are the reliability of inactivation and the minimum damaging effect on the antigens of bacteria and viruses.

Historically, heating was considered the first method of inactivation. (“warmed vaccines”).

The idea of "warmed vaccines" belongs to V. Kolle and R. Pfeiffer. Inactivation of microorganisms is also achieved under the action of formalin, formaldehyde, phenol, phenoxyethanol, alcohol, etc.

The Russian vaccination calendar includes vaccination with killed pertussis vaccine. Currently, the country uses (along with live) inactivated polio vaccine.

In healthcare practice, along with live ones, killed vaccines against influenza, tick-borne encephalitis, typhoid fever, paratyphoid fever, brucellosis, rabies, hepatitis A, meningococcal infection, herpes infection, Q fever, cholera and other infections are also used.

Chemical vaccines

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Chemical vaccines contain specific antigenic components extracted from bacterial cells or toxins by various methods (extraction with trichloroacetic acid, hydrolysis, enzymatic digestion).

The highest immunogenic effect is observed with the introduction of antigenic complexes obtained from the shell structures of bacteria, for example, the Vi-antigen of the causative agents of typhoid fever and paratyphoid fever, the capsular antigen of the plague microorganism, antigens from the shells of the pathogens of whooping cough, tularemia, etc.

Chemical vaccines have less pronounced side effects, they are actogenic, and retain their activity for a long time. Among the drugs of this group in medical practice, cholerogen is used - anatoxin, highly purified antigens of meningococci and pneumococci.

Anatoxins

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To create artificial active immunity against infectious diseases caused by microorganisms that produce exotoxin, toxoids are used.

Anatoxins are neutralized toxins that have retained antigenic and immunogenic properties. Neutralization of the toxin is achieved by exposure to formalin and prolonged exposure in a thermostat at a temperature of 39–40 °C. The idea of neutralizing the toxin with formalin belongs to G. Ramon (1923), who proposed diphtheria toxoid for immunization. Currently, diphtheria, tetanus, botulinum and staphylococcal toxoids are used.

In Japan, a cell-free precipitated purified pertussis vaccine has been created and is being studied. It contains lymphocytosis-stimulating factor and hemagglutinin as toxoids and is significantly less reactogenic and at least as effective as particulate killed pertussis vaccine (which is the most reactogenic part of the widely used DTP vaccine).

Third generation vaccines

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Currently, the improvement of traditional technologies for the manufacture of vaccines continues and vaccines are being successfully developed taking into account the achievements of molecular biology and genetic engineering.

The impetus for the development and creation of third-generation vaccines was the reasons due to the limited use of traditional vaccines for the prevention of a number of infectious diseases. First of all, this is due to pathogens that are poorly cultivated in in vitro and in vivo systems (hepatitis viruses, HIV, malaria pathogens) or have pronounced antigenic variability (influenza).

Third generation vaccines include:

synthetic vaccines,
genetic engineering and
anti-idiotypic vaccines.

Artificial (synthetic) vaccines

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Artificial (synthetic) vaccines are a complex of macromolecules that carry several antigenic determinants of various microorganisms and are capable of immunizing against several infections, and a polymer carrier is an immunostimulant.

The use of synthetic polyelectrolytes as an immunostimulant can significantly increase the immunogenic effect of the vaccine, including in individuals carrying low-response Ir-genes and strong suppression Is-genes, i.e. in cases where traditional vaccines are ineffective.

Genetically engineered vaccines

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Genetically engineered vaccines are developed on the basis of antigens synthesized in recombinant bacterial systems (E. coli), yeast (Candida) or viruses (vaccinia virus). This type of vaccine can be effective in the immunoprophylaxis of viral hepatitis B, influenza, herpes infection, malaria, cholera, meningococcal infection, opportunistic infections.

Anti-idiotypic vaccines

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Among the infections for which vaccines already exist or a new generation of vaccines are planned to be used, first of all, hepatitis B should be noted (vaccination was introduced in accordance with the order of the Ministry of Health of the Russian Federation No. 226 of 08.06.96 in the vaccination calendar).

Promising vaccines include vaccines against pneumococcal infection, malaria, HIV infection, hemorrhagic fevers, acute respiratory viral infections (adenoviral, respiratory syncytial virus infection), intestinal infections (rotavirus, helicobacteriosis), etc.

Monovaccines and combination vaccines

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Vaccines may contain antigens from one or more pathogens.
Vaccines containing antigens of the causative agent of one infection are called monovaccines(cholera, measles monovaccine).

Have been widely used associated vaccines, consisting of several antigens and allowing vaccination against several infections at the same time, di- and trivaccines. These include adsorbed pertussis-diphtheria-tetanus (DTP) vaccine, typhoid-paratyphoid-tetanus vaccine. Adsorbed diphtheria-tetanus (ADS) divaccine is used, which is vaccinated in children after 6 years of life and adults (instead of DTP vaccination).

Live associated vaccines include the measles, mumps and rubella (MTC) vaccine. A combined TTK and varicella vaccine is being prepared for registration.

Ideology of creation combined The vaccine is part of the World Vaccine Initiative, whose ultimate goal is to create a vaccine that could protect against 25-30 infections, be administered once by mouth at a very early age and would not cause side effects.

Over the centuries, humanity has experienced more than one epidemic that claimed the lives of many millions of people. Thanks to modern medicine, drugs have been developed to avoid many deadly diseases. These drugs are called "vaccine" and are divided into several types, which we will describe in this article.

What is a vaccine and how does it work?

A vaccine is a medical product containing killed or weakened pathogens of various diseases or synthesized proteins of pathogenic microorganisms. They are introduced into the human body to create immunity to a particular disease.

The introduction of vaccines into the human body is called vaccination, or inoculation. The vaccine, entering the body, induces the human immune system to produce special substances to destroy the pathogen, thereby forming its selective memory for the disease. Subsequently, if a person becomes infected with this disease, his immune system will quickly counteract the pathogen and the person will not get sick at all or suffer a mild form of the disease.

Methods of vaccination

Immunobiological preparations can be administered in various ways according to the instructions for vaccines, depending on the type of preparation. There are the following methods of vaccination.

The introduction of the vaccine intramuscularly. The vaccination site for children under one year old is the upper surface of the middle of the thigh, and for children from 2 years old and adults it is preferable to inject the drug into the deltoid muscle, which is located in the upper part of the shoulder. The method is applicable when an inactivated vaccine is needed: DPT, DPT, against viral hepatitis B and influenza vaccine.

Feedback from parents suggests that infants are better able to tolerate vaccination in the upper thigh than in the buttock. The same opinion is shared by physicians, conditioned by the fact that in the gluteal region there may be an abnormal placement of nerves, which occurs in 5% of children under one year old. In addition, children of this age have a significant fat layer in the gluteal region, which increases the likelihood of the vaccine getting into the subcutaneous layer, which reduces the effectiveness of the drug.

Subcutaneous injections are administered with a thin needle under the skin in the area of the deltoid muscle or forearm. An example is BCG, the smallpox vaccine.

The intranasal method is applicable for vaccines in the form of an ointment, cream or spray (measles, rubella).
The oral route is when the vaccine is placed in the form of drops in the patient's mouth (polio).

Types of vaccines

Today, in the hands of medical workers in the fight against dozens of infectious diseases, there are more than a hundred vaccines, thanks to which entire epidemics have been avoided and the quality of medicine has significantly improved. It is conventionally accepted to distinguish 4 types of immunobiological preparations:

Live vaccine (against polio, rubella, measles, mumps, influenza, tuberculosis, plague, anthrax).
Inactivated vaccine (against pertussis, encephalitis, cholera, meningococcal infection, rabies, typhoid, hepatitis A).
Toxoids (vaccines against tetanus and diphtheria).
Molecular or biosynthetic vaccines (for hepatitis B).

Types of Vaccines

Vaccines can also be grouped according to the composition and method of their preparation:

Corpuscular, that is, consisting of whole microorganisms of the pathogen.
Component or acellular consist of parts of the pathogen, the so-called antigen.
Recombinant: This group of vaccines includes the antigens of a pathogenic microorganism introduced using genetic engineering methods into the cells of another microorganism. A representative of this group is the flu vaccine. Another striking example is the hepatitis B vaccine, which is obtained by introducing an antigen (HBsAg) into yeast cells.

Another criterion by which a vaccine is classified is the number of diseases or pathogens it prevents:

Monovalent vaccines are used to prevent only one disease (for example, the BCG vaccine against tuberculosis).
Polyvalent or associated - for vaccination against several diseases (for example, DPT against diphtheria, tetanus and whooping cough).

live vaccine

A live vaccine is an indispensable drug for the prevention of many infectious diseases, which is found only in corpuscular form. A characteristic feature of this type of vaccine is that its main component is weakened strains of the infectious agent that can reproduce, but are genetically devoid of virulence (the ability to infect the body). They contribute to the body's production of antibodies and immune memory.

The advantage of live vaccines is that still alive, but weakened pathogens induce the human body to develop long-term immunity (immunity) to a given pathogenic agent even with a single vaccination. There are several ways to administer the vaccine: intramuscularly, under the skin, nasal drops.

The disadvantage is that a gene mutation of pathogenic agents is possible, which will lead to the disease of the vaccinated. In this regard, it is contraindicated for patients with especially weakened immunity, namely for people with immunodeficiency and cancer patients. Requires special conditions for transportation and storage of the drug in order to ensure the safety of living microorganisms in it.

Inactivated vaccines

The use of vaccines with inactivated (dead) pathogenic agents is widely used for the prevention of viral diseases. The principle of action is based on the introduction of artificially cultivated and viable viral pathogens into the human body.

“Killed” vaccines in composition can be either whole-microbial (whole-viral), subunit (component) and genetically engineered (recombinant).

An important advantage of "killed" vaccines is their absolute safety, that is, the absence of the likelihood of infection of the vaccinated and the development of infection.

The disadvantage is the shorter duration of immune memory compared to "live" vaccinations, also inactivated vaccines retain the likelihood of developing autoimmune and toxic complications, and the formation of a full-fledged immunization requires several vaccination procedures with maintaining the necessary interval between them.

Anatoxins

Toxoids are vaccines created on the basis of decontaminated toxins released during the life of some pathogens of infectious diseases. The peculiarity of this vaccination is that it provokes the formation of not microbial immunity, but antitoxic immunity. Thus, toxoids are successfully used to prevent those diseases in which clinical symptoms are associated with a toxic effect (intoxication) resulting from the biological activity of a pathogenic agent.

The release form is a clear liquid with a sediment in glass ampoules. Before use, shake the contents to evenly distribute the toxoids.

The advantages of toxoids are indispensable for the prevention of those diseases against which live vaccines are powerless, moreover, they are more resistant to temperature fluctuations and do not require special storage conditions.

Disadvantages of toxoids - they induce only antitoxic immunity, which does not exclude the possibility of the occurrence of localized diseases in the vaccinated, as well as the carriage of pathogens of this disease by him.

Production of live vaccines

Mass production of the vaccine began at the beginning of the 20th century, when biologists learned how to weaken viruses and pathogens. A live vaccine is about half of all preventive drugs used in world medicine.

The production of live vaccines is based on the principle of reseeding the pathogen into an organism that is immune or less susceptible to a given microorganism (virus), or cultivating the pathogen under unfavorable conditions with the impact of physical, chemical and biological factors on it, followed by the selection of non-virulent strains. The most common substrates for culturing avirulent strains are chicken embryos, primary cell cultures (chicken or quail embryonic fibroblasts), and transplantable cultures.

Obtaining “killed” vaccines

The production of inactivated vaccines differs from live vaccines in that they are obtained by killing rather than attenuating the pathogen. To do this, only those pathogenic microorganisms and viruses that have the greatest virulence are selected, they must be of the same population with clearly defined characteristics characteristic of it: shape, pigmentation, size, etc.

Inactivation of pathogen colonies is carried out in several ways:

overheating, that is, exposure to a cultivated microorganism at an elevated temperature (56-60 degrees) for a certain time (from 12 minutes to 2 hours);
exposure to formalin for 28-30 days while maintaining the temperature at 40 degrees, an inactivating chemical reagent can also be a solution of beta-propiolactone, alcohol, acetone, chloroform.

Making toxoids

In order to obtain a toxoid, toxogenic microorganisms are first cultivated in a nutrient medium, most often in a liquid consistency. This is done in order to accumulate as much exotoxin in the culture as possible. The next stage is the separation of the exotoxin from the producer cell and its neutralization using the same chemical reactions that are used for "killed" vaccines: exposure to chemical reagents and overheating.

To reduce the reactivity and susceptibility, antigens are cleaned of ballast, concentrated and adsorbed with alumina. The process of adsorption of antigens plays an important role, since an injection with a high concentration of toxoids forms a depot of antigens, as a result, antigens enter and spread throughout the body slowly, thereby ensuring an effective immunization process.

Destruction of unused vaccine

Regardless of which vaccines were used for vaccination, containers with drug residues must be treated in one of the following ways:

boiling used containers and tools for an hour;
disinfection in a solution of 3-5% chloramine for 60 minutes;
treatment with 6% hydrogen peroxide also for 1 hour.

Expired drugs must be sent to the district sanitary and epidemiological center for disposal.