Clinical recommendations for vaccine prevention of pneumococcal infection in adults

brief information

Diseases of pneumococcal etiology are an urgent problem in practical healthcare, which is due to the leading role of Streptococcus pneumoniae in the structure of respiratory tract infections.
According to experts from the World Health Organization (WHO), these are the most common bacterial infections in adults in the world. S. pneumoniae continues to be a leading cause of serious illness, including bacteremia, meningitis, and pneumonia. Representing a serious medical and social problem for many countries, pneumococcal infections (PI) are also relevant for Russia. At the same time, the problem of PI in our country is given clearly insufficient attention, despite the existing achievements in this area, the main one of which is the creation of effective methods for the prevention of these infections, aimed at reducing the costs of treating diseases caused by pneumococcus and mortality due to this reason. The effectiveness of vaccination against PI, proven in numerous studies, made it possible to consider this event as promising and recommended for inclusion in the Calendar of Preventive Vaccinations.

Vaccination against pneumococcal infection: who needs it and when to do it

The second release of the new cherinfo video project “Vaccination Calendar” is dedicated to vaccination against pneumococcal infection.

This vaccination was included in the National Calendar in 2014. According to the World Health Organization, pneumococcal infection is one of the leading causes of morbidity and mortality in the world.

“Pneumococcal infection is caused by bacteria from the category of cocci, and not by a virus, as many people think. This infection is spread through respiratory droplets, such as coughing. The source of infection can be a person who outwardly looks completely healthy. A person infected with pneumococcal infection can develop pneumonia, sepsis, meningitis, otitis media... The infection is often very difficult to tolerate. Therefore, vaccination is the most reliable tool in the fight against the spread of infection,” explained the chief physician of clinic No. 7, Evgenia Smirnova.

Most often, pneumococcal infection is contracted by adults in poor health and young children.

According to doctors, the main problem now is the increasing resistance of pneumococcus to antibiotics. Because of this, treatment is often ineffective and protracted.

“If a person develops pneumonia after infection, it can be very severe. There are many complications: respiratory failure, suppuration with the formation of abscesses, the development of pleurisy, but the most dangerous is death,” said Vera Novozhilova, a pulmonologist at the Severstal medical unit.

However, if you are vaccinated, the risk of developing pneumonia is minimal, doctors say.

Vaccination against pneumococcal infection is given free of charge to children under five years of age and adults over 60 years of age. The vaccine is administered to the child three times, starting at two months of age. Adults are vaccinated once. At the same time, for those who suffer from chronic diseases, doctors recommend repeating the vaccine every three years.

World experience has shown that mass vaccination reduces the incidence of pneumococcal meningitis and severe pneumonia in children by more than 80% and the incidence of all pneumonia and otitis by more than a third. Vaccinated children are less likely to become carriers of pneumococci; accordingly, children and adults who have not received the vaccine get sick less often. This data is provided by the World Health Organization.

“We are receiving the American vaccine Prevenar 13. The vaccination will protect against 13 strains of pneumococcal infection. Strains, if we draw an analogy, are like breeds of cats or dogs, that is, varieties of one microbe. I would like to separately note: if a child was born premature, with chronic pathologies, or has blood diseases, then vaccination against pneumococcal infection is especially indicated. The same can be said about adults. By the age of 60, an archive of pathologies accumulates, and it is vaccination that will protect a person from serious illness. In our country, unfortunately, many people think that weakened people do not need to be vaccinated,” worries Evgenia Smirnova.

The Prevenar 13 vaccine protects against the 13 most common types of pneumococcus, which cause up to 80% of pneumococcal infections.

The World Health Organization projects that global use of pneumococcal vaccinations will prevent at least 5.4 million child deaths by 2030.

In the next program we will talk in detail about vaccination against tick-borne encephalitis.

All episodes of the “Vaccination Calendar” program are posted on the channel of the Cherepovets news agency.

The project is released with the support of the government of the Vologda region.

Svetlana Marushchenko

Definition

Pneumococcal infection is a group of ubiquitous anthroponotic diseases caused by the presence of airborne bacteria S. pneumoniae, which can penetrate the usually sterile environment of the human body, causing serious pathology with high mortality. There are 2 forms of PI - invasive (iPI) (meningitis, pneumonia with bacteremia, septicemia, septic arthritis, osteomyelitis, pericarditis, endocarditis) and non-invasive (pneumonia without bacteremia, acute otitis media, sinusitis, etc.) forms.

Epidemiology and features of clinical forms

According to WHO, PV is recognized as the most dangerous of all vaccine-preventable diseases (VP); Moreover, before the introduction of universal vaccination, PI was the cause of death for 1.6 million people annually, of which 0.7 to 1 million were children.

The case fatality rate for iPI can be high, ranging from 20% for septicemia to 50% for meningitis in developing countries. Mortality rates are highest in young children and people over 65 years of age.

Pneumococcus plays a primary role as the causative agent of pneumonia. According to foreign and domestic authors, this pathogen is the cause of 25–35% of all community-acquired and 3–5% of hospital-acquired pneumonia.

Community-acquired pneumonia is most severe in the elderly (with age, a person becomes more susceptible to the development of severe infections), as well as against the background of concomitant diseases (chronic broncho-obstructive, oncohematological cardiovascular diseases, viral infections, diabetes mellitus (DM), kidney and liver diseases , infection with the human immunodeficiency virus (HIV), alcoholism, etc.) Thus, the risk of developing iPI increases in bronchial asthma (BA) by 2 times, chronic obstructive pulmonary disease (COPD) - by 4 times, pulmonary fibrosis - by 5 times, sarcoidosis and bronchiectasis – 2–7 times. A direct relationship has been established between the frequency of iPI and age, smoking, and treatment with systemic or inhaled glucocorticosteroids. Elderly patients have a 3–5 times higher risk of death from pneumonia and its complications compared to young people

Workers of industrial enterprises with professional contact with metal fumes, mineral or any other dust or gaseous substances experience a rapid spread of respiratory infections and a severe course of these diseases. Contamination of the work area with aerosol particles makes a significant contribution to the development and spread of not only sporadic cases of PI, but also group diseases.

Patients with COPD account for 20.5–25.7% of those hospitalized with community-acquired pneumonia, with 30-day mortality accounting for approximately 9.6% of cases. Among patients admitted to hospitals for pneumonia, 15.8% have coronary heart disease (CHD), 14.3% have chronic heart failure, 9.6% have diabetes, with a mortality rate of 15–30%. The pathogenesis of the development of cardiac complications in pneumococcal pneumonia, which can lead to death, has been proven. Pneumonia caused by S. pneumoniae is most often complicated by pulmonary empyema and leads to death (up to ⅔ cases for empyema). The life-threatening form of PI is pneumococcal sepsis with the development of severe shock damage to organs. In the Russian Federation, 60% of sick adults over the age of 65 die from pneumococcal meningitis.

The transmission mechanism of pneumococci is aerosol, the route of transmission is airborne. The pathogen is transmitted from a source to susceptible individuals through close contact, coughing, sneezing, etc.

Most cases of PI are sporadic. Outbreaks of PI are typical for persons in the so-called. organized (closed) groups (children's homes, kindergartens, schools, student dormitories, military groups, institutions of the penitentiary system, long-term hospitals, boarding schools, homes for the elderly, etc.). In these same groups, the highest level of pneumococcal carriage is determined.

The distribution of PI incidence by month is uneven; the maximum incidence rate is recorded in the cold period of time (November–February), the minimum in the warm months (July–August). The intra-annual dynamics of the incidence of PI correlates with that of influenza and acute respiratory diseases.

Vaccine prevention remains the main means of containing the spread of PIs today.

Characteristics of vaccines for the prevention of pneumococcal infection

Currently, for the purpose of specific prevention of diseases caused by pneumococcus, two types of vaccines are used in adults: polysaccharide 23-valent (PPV-23) and polysaccharide conjugated adsorbed 13-valent (PCV-13).

Polysaccharide vaccines

Polysaccharide vaccines contain highly purified capsular polysaccharides (25 μg each) as antigens that activate B lymphocytes, triggering the production of immunoglobulins (Ig) classes M and G. The basis of the action of PPV is a T-independent immune response. Immunity is acquired 10–15 days after a single vaccination and persists for ≥ 5 years.

Indications for use are diseases and conditions that predispose to the development of PI in persons over 2 years of age. Method of administration: subcutaneous or intramuscular (mainly) injection into the deltoid muscle of the shoulder.

Conjugate vaccines

The action of conjugate vaccines is based on a T-dependent response. As a result of the conjugation of polysaccharides with a carrier protein, a qualitatively different immune response is formed compared to PPV. The antigen-presenting cell recognizes the polysaccharide antigen by capturing the carrier protein, simultaneously processing and presenting it to T cells in combination with histocompatibility complex molecules.

What vaccines are used?

There are polysaccharide and conjugate vaccines. Polysaccharide ones contain a larger number of strains (varieties) of pneumococci, while conjugated ones are superior in terms of age-specific breadth of application and duration of protection.

In our center, we more often use conjugate drugs - those that are used from 2 months of age and provide long-term immunity, often lifelong.

Pneumococcal vaccines: Prevenar-13 or Synflorix.

They protect against invasive forms of the disease - peritonitis, endocarditis, meningitis, pneumonia, sepsis and form long-term immunological memory. In other words, the body knows, remembers and is ready for defense.

Specific vaccine prevention of pneumococcal infection

Vaccination is recognized as the most effective method of preventing PI. According to the WHO position, vaccination is the only way to significantly influence the morbidity and mortality from PI and reduce the level of resistance to ALD. Having confirmed the safety and effectiveness of pneumococcal vaccines, WHO and UNICEF experts consider it necessary to include pneumococcal vaccines with a proven safety and effectiveness profile in all national immunization programs.

When carrying out VP PI, it is necessary to be guided by the current regulatory and methodological documents on the organization of immunization, primarily the National Calendar of Preventive Vaccinations and the Calendar of Preventive Vaccinations for Epidemic Indications, as well as instructions for the use of immunobiological drugs.

In the Russian Federation, vaccination against PI of all adults over the age of 50 years and patients at risk (including HIV-infected patients) is currently included as a mandatory measure in clinical recommendations and standards of medical care for therapy, cardiology, neurology, oncology, oncohematology, nephrology, pulmonology, allergology, immunology, endocrinology and transplantology.

Vaccination against PI is aimed at preventing the occurrence of generalized forms of pneumococcal infection (iPI), pneumonia, reducing morbidity, disability and mortality of the population from these infections. According to WHO data for different countries, it has been convincingly shown that specific CAP is the most accessible and cost-effective way to prevent PI. This is also confirmed by the results of domestic research.

Risk groups for the development of pneumococcal infection in adults

Vaccination with the pneumococcal vaccine is recommended for individuals at high risk of developing iPI. Such patients can be divided into 2 groups: immunocompetent and immunocompromised.

The immunocompetent group includes the following patients:

with chronic bronchopulmonary diseases (COPD, asthma) with concomitant pathology in the form of chronic bronchitis, emphysema, with frequent relapses of respiratory pathology;
with cardiovascular diseases (coronary artery disease, heart failure, cardiomyopathy, chronic heart failure, etc.);
with chronic liver diseases (including cirrhosis);
with diabetes and obesity;
those sent and in special conditions of stay: organized groups (military personnel and conscripts, people working on a rotational basis, staying in places of detention, social institutions - homes for the disabled, nursing homes, boarding schools, etc.);
suffering from alcoholism;
smokers;
workers in industries that are harmful to the respiratory system (those with increased dust generation, flour mills, etc.), welders;
medical workers;
aged 65 years and older;
convalescents of acute otitis media, meningitis, pneumonia;

The immunocompromised group includes the following patients:

with congenital and acquired immunodeficiencies (including HIV infection and iatrogenic immunodeficiencies);
receiving immunosuppressive therapy, including immunobiological drugs, systemic glucocorticosteroids (≥ 20 mg prednisolone per day), antitumor drugs;
those suffering from nephrotic syndrome/chronic renal failure requiring dialysis;
with cochlear implants (or subject to cochlear implantation);
with leakage of cerebrospinal fluid;
those suffering from hematological malignancies receiving immunosuppressive therapy;
with congenital or acquired (anatomical or functional) asplenia;
suffering from hemoglobinopathies (including sickle cell anemia);
on the waiting list for or after organ transplantation.

Vaccination against pneumococcus

What is pneumococcus?

Pneumococcus (or Streptococcus pneumoniae - streptococcus pneumoniae) is a very common bacterium that causes diseases such as pneumonia (pneumonia), bronchitis, sinusitis, as well as such common infections as sepsis (blood poisoning), inflammation of the cerebral cortex (meningoencephalitis). ) and others.
Vaccination against pneumococcus on Tveritina

Vaccination of adults with the conjugate vaccine Prevenar 13. Cost including a doctor’s appointment is 3,500 rubles.

Why is vaccination needed?

A number of diseases and conditions are associated with an increased risk of severe disease and aggressive behavior of pneumococcus. To reduce this risk, vaccination is needed.

Who needs vaccination?

Groups at increased risk of developing severe forms of pneumococcal infection, such as:

All children under 2 years old.
All adults age 65 and older.
Patients with chronic diseases, for example, diabetes and other chronic metabolic disorders, heart and blood vessel diseases, hepatitis and/or cirrhosis of the liver or chronic lung diseases (COPD, asthma, etc.).
Persons with congenital or acquired immunodeficiency, including oncohematological diseases, malignant neoplasms and HIV infection.
Persons with spleen disorders (including sickle cell disease) or who have had their spleen removed or are preparing to have their spleen removed.
Persons who have undergone an organ transplant or bone marrow transplant.
Persons with chronic renal failure or nephrotic syndrome, as well as those on dialysis.

What types of vaccines are there?

In the Russian Federation there are two types of vaccines that do not contain live pathogens:

Pneumococcal conjugate vaccine (PCV13) . This is a vaccine containing a protein associated with the membrane components of 13 strains of pneumococcus. This includes Prevenar 13 and Synflorix . PCV13 is recommended for all children under 2 years of age and people 2 years of age and older with certain medical conditions. Adults 65 years of age and older can also talk to their doctor about getting the PCV13 vaccine.
Pneumococcal polysaccharide vaccine (PPSV23) . This is a vaccine containing components of the polysaccharide shell of 23 strains of pneumococcus. This includes Pneumovax 23 . PPSV23 is recommended for all adults 65 years of age and older, people 2 to 64 years of age with certain medical conditions, and adults 19 to 64 years of age who smoke tobacco. Children younger than 2 years of age should not receive this vaccine.

What vaccination regimen is used?

For adults at risk, one dose of conjugate vaccine (Prevenar 13) is recommended. Persons from particularly high-risk groups should receive two doses of a polysaccharide vaccine (Pneumovax 23) in addition to the conjugate vaccine. In such cases, it is recommended to start with a series of conjugate vaccines, and then vaccinate with a polysaccharide vaccine.

A second dose of Pneumovax vaccine (5 years after the first dose) is recommended for vaccinated individuals at particularly high risk of severe pneumococcal disease. It is recommended to do this vaccination one more time.

For people 65 years of age and older who received one dose of vaccine before age 65, an additional dose is recommended when they turn 65 (if at least 5 years have passed since their last dose).

Vaccination against pneumococcus on Tveritina

Vaccination of adults with the conjugate vaccine Prevenar 13. Cost including a doctor’s appointment is 3,500 rubles.

How well do these vaccines work?

Some pneumococcal infections are invasive. Invasive disease means that germs invade parts of the body that are usually free of germs. Invasive disease is usually very serious and can lead to death.

Vaccines that help protect against pneumococcal disease work well but may not prevent all cases.

Studies show that at least 1 dose of pneumococcal conjugate vaccine protects:

At least 8 out of 10 children suffer from a serious infection called invasive pneumococcus.
75 out of 100 adults aged 65 years and older against invasive pneumococcal disease.
45 out of 100 adults aged 65 years and older against pneumococcal pneumonia.

Research* shows that 1 dose of pneumococcal polysaccharide vaccine protects

50 to 85 out of 100 healthy adults against invasive pneumococcal disease.

What are the side effects of pneumococcal vaccinations?

Prevenar

10 - 20% of people who receive the vaccine experience local side effects - redness, swelling or pain in the injection area. In more rare cases, a short-term fever or feeling of restlessness may occur. Very rare side effects include seizures, lethargy and sensitivity (0.01 - 0.1% of cases). Side effects such as a severe allergic (anaphylactic) reaction are extremely rare.

Pneumovax

The most common side effects are local, while rarer ones include temporary fever, muscle pain, weakness and vomiting. Cases of hypersensitivity are rare.

Vaccination against pneumococcus on Tveritina

Vaccination of adults with the conjugate vaccine Prevenar 13. Cost including a doctor’s appointment is 3,500 rubles.

What interval should be observed when performing pneumococcal vaccinations in relation to other vaccinations?

Pneumococcal vaccinations can be given at the same time as other vaccinations, or at any time before or after them.

What is the recommended interval between Prevenar and Pneumovax vaccinations?

For persons over 18 years of age, it is recommended to administer Prevenar, followed by Pneumovax after 8 weeks. If vaccination begins with Pneumovax and then Prevenar is administered, then the recommended interval between them should be one year.

When should you not get vaccinated against pneumococcus?

If you or your child have had a life-threatening allergic reaction or severe allergy to vaccines.
People with a mild illness, such as a cold, can probably get the vaccine. People with more serious illness should probably wait until they have recovered. Consult your doctor in this situation.

Can pneumococcal vaccination be given at the same time as influenza vaccination?

Immunization against pneumococcus can be carried out throughout the year. If you plan to organize a mass vaccination program against influenza, then it is convenient to carry out this vaccination simultaneously with immunization against pneumococcal infection before the start of the acute respiratory infections and influenza season, which corresponds to the recommendations of the World Health Organization.

Is it possible to get vaccinated during pregnancy?

There is no evidence that PCV13 or PPSV23 is harmful to pregnant women or the fetus. However, as a precaution, women who need the vaccine should get it before pregnancy if possible.

Vaccination of persons classified as risk groups

Immunization against PI is carried out throughout the year. If you plan to organize a mass vaccination program against influenza, then it is convenient to carry out this vaccination simultaneously with immunization against PI before the start of the season of acute respiratory diseases and influenza, which corresponds to WHO recommendations.

Immunization against PI is necessary for people of any age at risk of developing iPI. Patients with impaired immunological reactivity or due to the use of immunosuppressive therapy, genetic defects, HIV infection or other reasons may experience a reduced humoral immune response to vaccination.

In immunocompromised patients of any age, a single vaccination with PPV-13 is initially recommended, and then (no earlier than 8 weeks later) with PPV-23; after 5 years, repeated administration of PPV-23 is necessary.

Contraindications to vaccination

The main contraindications for vaccination against PI are the following:

pronounced, severe systemic reactions to the previous administration of the vaccine (anaphylactic reactions);
hypersensitivity to any component of the vaccine;
acute infectious diseases or exacerbation of a chronic process (the underlying disease).

Vaccination can be carried out after 1–2 weeks. after achieving remission or recovery from an acute infectious disease. Previous PI is not a contraindication to immunization.

Post-vaccination reactions

Overall, the incidence of serious adverse events reported within 1 month. after vaccine administration was <2%. No significant differences were observed with both vaccines.

Most often (about 20% of cases of all adverse events) in the post-vaccination period of PCV administration the following reactions occur: fever, rarely exceeding 39 ° C, excitability, loss of appetite and sleep disturbance, as well as local reactions in the form of swelling, hyperemia, soreness, thickening of the site of vaccine administration. A significant proportion of these reactions develop in the first 48 hours after vaccination and stop on their own or with the use of antipyretic and antihistamine drugs.

When performing PPV vaccination, it is possible to develop post-vaccination reactions of varying severity during the first 3 days, among which local reactions in the form of pain, redness, thickening or swelling at the injection site are most often observed. Severe local reactions such as the Arthus phenomenon are very rarely described in people who have previously had PI and, as a result, have a high level of specific antibodies. A moderate increase in body temperature can persist from several hours to 3 days after vaccination. In very rare cases, other general reactions may develop - adenopathy, arthralgia, rash and allergic reactions (urticaria, Quincke's edema, anaphylactic reaction).

After administration of the vaccine, as with all injectable vaccines, you should always be prepared to provide appropriate medical care and monitoring in the event of an anaphylactic reaction.

Features of vaccination of people with chronic diseases

Vaccinations are carried out under the supervision of a doctor at the immunoprophylaxis office. After vaccination, the patient should be observed for ≥ 30 minutes.
Vaccination is carried out against the background of anti-relapse (basic) therapy in consultation with a specialist. Vaccinations are carried out every 2–4 weeks. after stabilization of the process or the beginning of remission when stable clinical symptoms and target hemodynamic parameters are achieved. Exceptions are complicated myocardial infarction or its relapse (after 28 days), chronic heart failure (7 days after the end of titration of diuretics with a stable patient’s body weight), dilated cardiomyopathy (after control of hemodynamics for 4 weeks and in a stable condition without syndrome hemodynamic decompensation).
When vaccinating children and adults with damage to the nervous system, especially with a history of febrile convulsions, it is recommended to measure the temperature after vaccination 3-4 times a day for the first 3 days; antipyretics are prescribed according to indications.
In patients with diabetes, vaccination against PI is carried out in the absence of complaints of thirst, polyuria, loss of appetite, fasting sugar level ≤ 10–12 mmol/l, daily glucosuria

≤ 10–20 mg, absence of ketone bodies in urine. The vaccine is administered deeply intramuscularly into areas free from lipodystrophy. When vaccinated, no dose adjustment of glucose-lowering drugs or insulin is required.

For kidney diseases, vaccination is carried out during the period of clinical and laboratory remission in patients whose estimated glomerular filtration rate (eGFR) is 30–59 ml/min/1.73 m2 (eGFR category C3) and <30 ml/min/1.73 m2 (eGFR categories C4–C5). Patients receiving replacement therapy with hemodialysis or peritoneal dialysis are vaccinated on a day free from these procedures.
When planning the administration of immunosuppressive drugs, vaccination should be carried out 4-6 weeks in advance. before the start of immunosuppressive therapy or after 3–6 months. at the end of radiation or chemotherapy.
In patients with HIV infection, vaccination is carried out during the period of remission of chronic diseases (after 2–4 weeks) with a CD4 T-lymphocyte count ≥ 200 cells/mm3.

Features of vaccination of persons with allergic diseases

Vaccination is carried out under the supervision of a doctor at the immunoprophylaxis office. After vaccination, the patient should be observed for ≥ 30 minutes.
Strict adherence to a diet with the exclusion of products to which allergic reactions have previously been noted, “obligate” allergens (chocolate, honey, nuts, fish, citrus fruits, strawberries, products with dyes and preservatives), as well as strict maintenance of a hypoallergenic lifestyle for 1 week. before vaccination and within 2 weeks. after her.
Vaccination is performed after 2–6 weeks. (depending on the pathology) after achieving stabilization of the process, control of the disease or the onset of remission. Basic therapy for an allergic disease, agreed upon with an allergist, is carried out, against the background of which control over the disease is achieved.
Antihistamines are prescribed for 1–2 weeks. before vaccination (depending on the nosological form) and 4–5 days after it.
Skin testing with allergens can be completed within 1–1.5 weeks. before and after 1 month. after vaccination.
A course of allergen-specific immunotherapy can begin after 2 weeks. after vaccination.

Contraindications

Only a doctor can decide whether Prevenar is suitable for a child to be vaccinated

Prevenar vaccination is contraindicated if there is a history of an allergic reaction to any component of the vaccine, as well as in the following cases:

Hypersensitivity reactions to previous administration of Prevenar drugs (including anaphylactic shock, severe generalized allergic reactions);
Hypersensitivity to diphtheria toxoid and/or excipients;
Acute infectious or non-infectious diseases, exacerbation of chronic diseases (vaccination is carried out after recovery or during remission).
If an acute or exacerbation of a chronic disease occurs, the child receives a deferment until complete recovery or a period of remission. The pediatrician determines the required duration of delay from vaccinations, guided primarily by the risk of complications. In most cases, the delay is about 1 month. In case of meningococcal meningitis and other severe diseases of the nervous system, vaccinations are postponed for a longer period - up to six months from the onset of the disease.
The main contraindications to vaccination, which provide grounds for medical withdrawal from vaccinations, are strong reactions and post-vaccination complications after the administration of the previous dose of the vaccine. A strong reaction is understood as an increase in body temperature above 40 °C with the occurrence of swelling and redness at the site of vaccine administration over 8 cm in diameter, severe allergic reactions, anaphylactic shock, the development of infectious diseases and damage to individual body systems.

The effectiveness of vaccine prevention

The effectiveness of any preventive measure, including CAP, is the degree to which the desired result is achieved through the implementation of this measure in the absence of side effects or their presence within established limits. The epidemiological, economic and social effectiveness of VP are highlighted.

The epidemiological effectiveness of CAP is determined by the degree of its influence on the epidemic process and is manifested in reducing morbidity and preventing the occurrence of new cases of infection among the population. When considering the epidemiological effectiveness of an event, it is customary to evaluate its potential and actual effectiveness.

The potential effectiveness of the VP is assessed by 2 main indicators: the efficiency index and the efficiency coefficient, or security indicator.

The index of the effectiveness of VP against a particular infection is the ratio of morbidity rates in the group of those vaccinated and those not vaccinated with this drug. It shows how many times the incidence rate of vaccinated individuals is lower than that of unvaccinated individuals.

The effectiveness coefficient characterizes the proportion of vaccinated individuals whose protection from infection was ensured by vaccination with this drug. The effectiveness coefficient is the most preferable indicator, since it shows only the effect of vaccination, without the influence of other preventive factors that may occur in the control and experimental groups.

The actual epidemiological effectiveness of CAP is determined by the actual reduction and prevention of morbidity as a result of CAP with a specific drug according to a specific regimen. The actual epidemiological effectiveness of VP is assessed during the period of its mass use. Assessing the actual effectiveness of EP is not a one-time study, but an ongoing analysis during epidemiological surveillance of infection, being a component of operational and retrospective epidemiological analyses.

The potential epidemiological effectiveness of VAP depends primarily on the immunogenicity of the vaccine, as well as on the choice of vaccination tactics and vaccination schedule.

The actual epidemiological effectiveness, assessed in real practical healthcare conditions with mass CAP, is usually lower than the potential effectiveness tested with optimal organization. The actual effectiveness is largely determined by the quality of the drug used and the quality of the organization and conduct of the event. The greater the difference between potential and actual effectiveness, the more reasons to doubt the quality of the means and measures and strengthen control over the EP. However, differences in effectiveness may be due to other reasons, for example, changes in the epidemiological situation, the evolution of the epidemic process of infection, which require changes in vaccination tactics.

The epidemiological effectiveness of VP PI has been assessed in numerous studies. Evidence in favor of the epidemiological effectiveness of vaccination is the decrease in the incidence of PIs in general and individual infections, primarily iPIs, recorded in various regions of the world.