Flu vaccination: how it works, why is it needed, when to do it?

• Composition of the influenza vaccine.
• How is vaccine safety achieved?
• Preventive vaccinations against influenza.
• How does the body react to the vaccine?
• Contraindications for flu vaccination.
• You can't get a flu shot if...
• Reaction to vaccination.
• Vaccines to prevent influenza.
• Names of the flu vaccine.

Influenza vaccination is used to prevent the spread of viruses in communities.
Flu vaccination is especially recommended in closed institutions such as schools, kindergartens, supermarkets, and hospitals. Properly administered flu vaccination prevents the spread of the virus and interrupts the chain of its transformation. As practice shows, if more than 40% of team members have received a flu vaccine, then the number of people who get sick among unvaccinated people does not exceed 10%. The flu virus is constantly changing, so a new vaccine is developed every year. After its administration, the body produces protective antibodies within two weeks, which last for a whole year. If a person gets sick after vaccination, then in this case the flu occurs in a milder form.

There are categories of people who should be vaccinated first:

• People over 60 years old;
• Patients with chronic somatic (not mental) diseases;
• Frequently suffering from acute respiratory infections;
• For preschool children and schoolchildren;
• Employees of medical institutions, workers in the service sector, transport, educational institutions.

How dangerous is the flu?

There is probably no person who does not suffer from ARVI. According to WHO, every person gets a cold from 2 to 4 times a year, school-age children - 4-5 times, preschoolers - 6 times a year, and babies in their first year of life - from 2 to 12 times. Among ARVI, the influenza virus is truly dangerous, which is why its prevention and treatment is given such great importance. Flu can lead to viral pneumonia and severe intoxication. It also leads to decreased immunity and exacerbation of chronic bacterial infections, bronchial asthma, cardiovascular diseases, and kidney diseases. All this, in turn, can lead to death. Therefore, patients with symptoms of severe intoxication, meningitis, acute respiratory and heart failure, high fever for more than 5 days, and pregnant women must be hospitalized in the infectious diseases department.

The best imported

Imported vaccines on the Russian market in the 2020–2021 season are represented by two drugs: the French Vaxigripp and the Dutch Influvac. According to RBC, they are expected in pharmacies in mid-October - early November.

Vaxigrip

Among the characteristics:

• Manufacturer: SANOFI PASTEUR, SA, France.
• Quadrivalent inactivated influenza split vaccine.
• Contains 15 mcg of influenza virus antigens of each strain, which is recommended by WHO.
• Does not contain adjuvants or preservatives.
• The minimum age for vaccination is 6 months.

Influvac

Among the characteristics:

• Manufacturer: Abbott, Netherlands.
• Quadrivalent subunit inactivated.
• Contains 15 mcg of influenza virus antigens of each strain, which is recommended by WHO.
• Does not contain adjuvants or preservatives.
• The minimum age for vaccination is 6 months.

How does the flu vaccine work?

There are several types of vaccines:

• vaccines containing live attenuated strains of viruses;
• vaccines containing dead viruses or fragments of viruses and antibodies to them.

Modern vaccines are tri- and quadrivalent, i.e. containing three or four types of viruses predicted by the World Health Organization for this particular year for a particular region. After vaccination, the body’s immune system begins to react, producing special antibodies that recognize and kill the virus when it enters the body. This process usually takes about a month, so vaccination takes place 1 - 1.5 months before the expected epidemic.

Is it possible to get vaccinated if you are allergic to chicken egg white?

Vaccine strains of the virus are grown on chicken egg whites. After cultivation, the drug is thoroughly cleaned of protein residues, but its microparticles are able to penetrate into the finished vaccine.

A number of studies have shown that the vaccine can only be dangerous if a person has an anaphylactic reaction to the eggs. A severe or moderate reaction to the protein does not in any way affect the tolerability of the vaccine. However, the final decision regarding a particular person always remains with the attending physician.

Who is recommended for the flu vaccine?

• children over 6 months old, especially those attending nurseries, kindergartens, schools;
• medical workers;
• employees of children's educational institutions (teachers, educators, heads of clubs, sections);
• elderly people over 60 years of age;
• chronic patients with diseases of the respiratory and cardiovascular systems;
• patients with reduced immunity.

Vaccination is mandatory for all these population groups. The vaccine will prevent you from getting sick or get through the disease more easily, and will prevent complications from developing.

Relevance

According to the World Health Organization (WHO), influenza and acute respiratory viral infections (ARVI) of various etiologies are the main cause of morbidity and mortality in all age groups of the population and consistently occupy first place among all known human infectious diseases.
Annual influenza epidemics cause serious harm to all age groups of the population. The highest risk of complications is observed among children younger than 2 years of age, adults aged 65 years and older, and people of any age with various medical conditions such as chronic heart, lung, kidney, liver, blood or metabolic disorders (diabetes, etc.) .). The particular danger of the influenza virus is its ability to suppress the body’s immune responses and increase the severity of chronic diseases, causing their decompensation [1]. The ability of influenza viruses to quickly spread among the population, travel significant distances in a short time and simultaneously infect large groups of people, the severity of clinical manifestations and the frequent occurrence of secondary complications make it difficult to carry out effective preventive and therapeutic measures. Among all medical measures implemented in the fight against infectious diseases, especially those transmitted by airborne droplets, vaccine prevention remains the most effective.

The role of vaccination

Modern influenza vaccines, according to the average WHO estimate, when the vaccine and circulating strains match, provide a reduction in the incidence of influenza among adults by 70–90%, a reduction in the risk of serious complications primarily in the elderly by 70–85%, and a 56% reduction in the incidence of others ARVI, the number of hospitalizations associated with influenza complications is reduced by 48%.

WHO documents recognize annual vaccination as the main measure to combat influenza epidemics. There is a lot of data indicating that influenza vaccines, prepared from vaccine strains of the influenza virus that are relevant for a given season and applied at the right time, can protect about 80% of healthy children and adults from influenza [2], as well as reduce the incidence of post-influenza complications . In older people, protection from influenza may be slightly lower, but mortality is significantly reduced [3].

Types of flu vaccines

For immunization against influenza in Russia, live (LAIV) and inactivated (IGV) influenza vaccines of domestic and foreign production are used.

LAIV reproduces a weakened natural infection in the body, promotes, as in the natural infectious process, the formation of many protective factors, both specific and nonspecific: early (within the first 4 days) - macrophages, natural killers, T-killers (CTL - cytotoxic T-lymphocytes, type I), interferon; and late (after the 4th day) - cytotoxic macrophages, type II CTLs, delayed hypersensitivity cells (types I and II) and finally antibodies, incl. secretory (class of immunoglobulins A - IgA) [4, 5]. In Russia, LAIV Ultravac is produced by a branch of the Federal State Unitary Enterprise NPO Microgen of the Russian Ministry of Health (Irkutsk), the vaccine is used intranasally once for adults and children over 3 years of age.

IVIs form predominantly humoral immunity, providing protection against influenza, and have fewer contraindications, which makes it possible to use them not only in practically healthy people, but also in people suffering from various chronic diseases, as well as people over 65 years of age. There are three main types of IVI: whole virion, split and subunit.

Modern IVIs are among the most high-tech and safe vaccine preparations. Existing production technologies make it possible to obtain highly purified drugs without preservatives and antibiotics, containing only protective antigens of the virus, responsible for the induction of specific immunity [6].

Each of the domestic IVIGs is characterized by good tolerability, as evidenced by the extensive experience of their use in Russia for more than 20 years.

Since 2015, to vaccinate the Russian population against influenza, along with the existing inactivated polymer-subunit influenza vaccines Grippol (JSC NPO Microgen) and Grippol Plus (LLC NPO Petrovax Pharm), which include azoximer bromide (Polyoxidonium), The vaccines used are Ultrix, an inactivated split vaccine produced by FORT LLC, and Sovigripp, an inactivated influenza subunit vaccine produced by NPO Microgen JSC. The Sovigripp vaccine includes the modern adjuvant Sovidon, which has immunomodulatory, detoxifying, antioxidant and membrane protective properties.

Calendar of preventive vaccinations against influenza

In accordance with the Federal Law of the Russian Federation “On Amendments to Art. 9 of the Federal Law “On Immunoprophylaxis of Infectious Diseases” No. 91-FZ dated June 30, 2006, influenza vaccination in Russia is included in the National Calendar of Preventive Vaccinations. In accordance with the Order “On approval of the national calendar of preventive vaccinations and the calendar of preventive vaccinations for epidemic indications” No. 125N dated 03/21/2014 of the Ministry of Health of Russia, children from 6 months of age, students of grades 1–11, studying in vocational institutions are subject to vaccination against influenza in the Russian Federation education and universities, adults working in certain professions (workers of medical and educational institutions, transport, public utilities), adults over 60 years of age, pregnant women, persons subject to conscription for military service, persons with chronic diseases, incl. with lung diseases, cardiovascular diseases, metabolic disorders and obesity.

According to WHO estimates, to prevent an epidemic, at least 30% of the population must be vaccinated against influenza. Vaccination coverage in Russia has been constantly increasing in recent years. During the epidemic season of 2015–2016. in the country as a whole, 44.9 million people were vaccinated, which amounted to 31.3% of the country’s total population [7].

During the 2016–2017 season. 55.9 million people have already been vaccinated (38.2% of the population), incl. more than 15 million children, 143.4 thousand pregnant women. In 28 constituent entities of the Russian Federation, a vaccination coverage level of 40% or more has been achieved. In the country as a whole, in 2016, influenza immunization coverage among risk groups increased by 2–8% and amounted to 41% for children from 6 months to 6 years, 63.8% for children from 7 to 17 years, 49 for medical workers, 3%, persons over 60 years old – 44.6%. However, the level of vaccination coverage among older people has not reached the WHO recommended level (at least 75%) [8]. During the 2017–2018 season. In Russia, more than 67.4 million people were vaccinated – 46.6% of the total population.

In the country as a whole, 85% of employees of educational institutions and persons subject to conscription for military service, and 89% of medical workers were vaccinated. However, among students and people over 60 years of age, this figure was 70 and 63%, respectively [9, 10]. At the board of Rospotrebnadzor following the results of the epidemic season on influenza and ARVI 2018–2019, which took place on April 19, 2019, the Federal Service for Surveillance on Consumer Rights Protection and Human Welfare noted that 49% of the entire population of the country was vaccinated against influenza. This is the highest level of coverage of the population with preventive vaccinations against influenza in the entire history of vaccination campaigns against influenza, incl. in risk groups [11]. There is an inverse relationship - the higher the vaccination coverage, the lower the incidence of influenza. After influenza vaccination was introduced into the National Vaccination Calendar in Russia in 2006, a decrease in the incidence of this infection was noted.

Assessing vaccine effectiveness

The main criterion for the quality of vaccines is their preventive effectiveness, which depends on the following factors:

1. Properties of influenza viruses associated with the rate of evolution of viruses. What is important here is the degree of antigenic correspondence between vaccine and epidemic strains of the virus.
2. Characteristics of the vaccine preparation - type of vaccine, antigenic load, biological activity, route of administration, frequency of immunization, quality of the vaccine preparation.
3. Characteristics of the individual - age, health status, genetic differences in immune response.
4. Epidemiological characteristics - vaccination coverage, timing of the onset of the epidemic, intensity of the epidemic, state of population immunity.

Flu vaccines require frequent updates to keep up with ever-changing circulating viruses, so the effectiveness and sometimes safety of the vaccine can vary from season to season. The flu vaccine is most effective when circulating viruses match well with the viruses contained in the vaccines. Among healthy adults, the influenza vaccine provides protection even if circulating viruses do not exactly match those of the vaccine. Among older adults, influenza vaccination may be less effective in preventing illness but reduces illness severity, complications, and death. Vaccination is especially important for people at high risk of complications from influenza and for those who live with or care for people at high risk for complications. According to most researchers, vaccination is indicated even if there is an incomplete match between the vaccine and circulating influenza virus strains, but its effectiveness may vary from season to season.

In the vast majority of countries, IVI is used to prevent influenza. Influenza viruses A(H1N1)pdm09 and A(H3N2) became widespread in Europe from October 2022 to January 2022. Interim results from six European studies showed that the effectiveness of the influenza vaccine during the 2018–2019 influenza season. among all ages was 32–43% against influenza A, while it was higher against A(H1N1)pdm09 and lower against A(H3N2). Among hospitalized older adults, vaccine effectiveness was between 34% and 38% against influenza A overall and slightly lower against A(H1N1)pdm09. Thus, the authors conclude that influenza vaccination was certainly beneficial during the 2018–2019 influenza season. [12].

Similar results were obtained in the previous influenza season [13]. Influenza A(H1N1)pdm09, A(H3N2) and B viruses circulated in Europe between September 2022 and February 2022. The results of five European studies show that influenza vaccine effectiveness in all age groups in the 2017–2018 season. ranged from 25 to 52% against any influenza, 55 to 68% against influenza A(H1N1) pdm09, 42 to 7% against influenza A(H3N2), and 36 to 54% against influenza B. The authors believe that current influenza vaccines , as a rule, work better against influenza B and influenza A(H1N1) viruses, and provide lower protection against influenza A(H3N2) viruses.

In the United States, annual seasonal influenza vaccination is recommended for all persons 6 months of age and older [14]. Since the 2004–2005 season. The CDC (Centers for Disease Control and Prevention, USA) annually evaluates the effectiveness of the seasonal influenza vaccine in preventing laboratory-confirmed influenza. A report by B. Flannery, JR Chung, EA Belongia, HQ McLean et al. provides an analysis of data on the effectiveness of influenza vaccine for a cohort of 4,562 children and adults from November 2, 2022 to February 3, 2018. During that period, the overall adjusted effectiveness of vaccines against influenza A and influenza B was 36% (27–44%). The majority (69%) of influenza illnesses were caused by A(H3N2) viruses. In their work, the authors emphasize the need for constant measures to prevent influenza and show that even with such effectiveness, vaccination will still prevent influenza disease, incl. thousands of hospitalizations and deaths [15, 16]. Similar data on the effectiveness of vaccines were obtained during the 2018–2019 epidemic season. [17]. The overall adjusted effectiveness of influenza vaccines was 47% (34–57%). For children aged 6 months to 17 years, the rate was 61% (44–73%). A(H1N1)pdm09 viruses were the cause of illness in 74% of influenza A patients for whom virus subtype information was available. Vaccine efficacy was 46% (30–58%). The CDC recommends that healthcare providers continue to administer inactivated influenza vaccines even during an epidemic because the vaccine can still prevent illness, hospitalization, and death associated with viruses currently circulating or other influenza viruses that may circulate later in the season.

Vaccination helps reduce the severity of influenza disease [18] and plays an important role in preventing influenza-related hospitalizations. The aim of the study by D. Zhang, Y. Zhang, Q. Wang et al. was to evaluate the effectiveness of vaccination in protecting Beijing residents aged 60 years and older from influenza causing hospitalization during the 2016–2017 and 2017–2018 influenza seasons. gg. Patients whose illness met the definition of severe acute respiratory infection (SARI) and were admitted to 9 sentinel hospitals in Beijing were included in the study population. A total of 50,364 patients were followed up and their vaccination status was obtained from the vaccination registry. The most frequently identified subtype was influenza A(H3N2) - 78.5 and 70.6% in the 2016–2017 and 2017–2018 seasons. respectively. The adjusted vaccine effectiveness against any type of influenza virus in the first observation period was 32.8% (from 22.0 to 63.0%) and was lower in the second observation period. The authors concluded that among hospitalized adults aged 60 years and older with influenza in Beijing, the influenza vaccine provided moderate protection in the 2016–2017 season. and soft protection in the 2017–2018 season. [19].

Assessment of the safety and effectiveness of multiple vaccinations

Extremely relevant at present is the scientific assessment of the safety and effectiveness of repeated vaccinations of the same people with influenza vaccines of the same type in antigenic composition in the context of the accepted tactics of influenza vaccine prevention in the form of mass annual vaccinations of the population. In an effort to achieve the maximum reduction in morbidity, annual revaccinations are recommended for the maximum possible number of people who do not have medical contraindications to vaccination. Epidemiological observations conducted in the 1970–1980s showed that primary vaccination and subsequent annual IIV vaccinations (booster vaccinations) differed significantly in immunological parameters. It has been noted that with annual immunization of people, immunogenicity and preventive effectiveness decrease rapidly. In foreign literature, this phenomenon is called the “Hopkins paradox.” The decrease in the immunological and epidemiological effectiveness of IVI for repeatedly vaccinated people argued for the need to reduce the number of annual vaccinations.

These results were demonstrated in repeated observations in organized groups of adults and children in schools, including studies by employees of the Influenza Research Institute in previous years [20–22]. It was shown that with long-term use of IVI, the most effective was the 2nd annual vaccination, which ensured a 2.5-fold reduction in the incidence of influenza and acute respiratory diseases (ARI) in the years of greatest antigenic matching of vaccine and epidemic viruses. The 1st and 3rd vaccinations were somewhat less effective, and the 4th and subsequent annual vaccinations were practically ineffective.

To be fair, it should be noted that observations of a decrease in the effectiveness of IVI vaccinations with multiple annual revaccinations applied to first-generation vaccines with a low antigen load. In more recent studies, W. E. Beyer, J. A. de Bruij, A. M. Palache et al. The “Hopkins paradox” is called into question [23].

Vaccine rotation schedules

Also, in the above-mentioned works by employees of the Influenza Institute, information was obtained that each subsequent injection of viral proteins is accompanied by an increasingly distinct influence of IIV suppressive factors. It was recommended to take a break of no more than 2 years after 2–3 annual IVIg vaccinations, because with a longer period, the incidence increases again [24].). During this period, it is advisable to revaccinate with LAIV, which can only affect people who are not immune to influenza. Since LAIV is injected into a cavity that naturally communicates with the external environment, the vaccine, which is not inoculated into the body of immune individuals, will not harm them. The advantage of the alternation scheme was shown in the study of epidemiological effectiveness and was expressed in a decrease in the incidence of disease cases, and was also manifested in a greater reduction in the number of days of disability in patients. When LAIV was administered, previous IV vaccinations did not inhibit the stimulation of local secretory immunity of the respiratory tract. Alternating vaccinations with IV and LAIV allows you to harmoniously stimulate various mechanisms of anti-influenza immunity. We believe that in modern conditions, the method of alternating IIV and LAIV vaccinations has a right to exist and provides certain advantages, manifested in increasing the effectiveness of vaccination and improving methods of influenza prevention.

Assessing the effectiveness of annual influenza vaccinations

In recent studies, authors' opinions on the effectiveness of annual flu shots have also been mixed. Many researchers confirm the effectiveness of vaccination in the current season, regardless of the presence or absence of vaccination in the previous season. L. C. Ramsay et al. 3435 unique articles were reviewed, 20 of which were included in the meta-analysis. Three groups of IIV vaccinated people were considered depending on their vaccine status: those who received the vaccine only in the current season, those vaccinated two years in a row, and those vaccinated only in the previous season [25]. There was no evidence of a negative effect of previous vaccination on the effectiveness of subsequent vaccinations. The authors emphasize the importance that future studies of vaccine effectiveness include vaccination history to be able to evaluate booster vaccination in more detail.

HQ McLean et al. studied the effect of booster vaccination on vaccine effectiveness against influenza A(H3N2) and B over eight seasons. From 2004–2005 to 2012–2013 patients with acute respiratory infections were under observation [26].

Depending on the vaccination history, the effectiveness of the vaccine in those vaccinated was assessed only during the current season, only during the previous one, and also took into account the presence or absence of immunization in the previous five seasons. Vaccine efficacy was calculated for participants aged 9 years and older. The results showed that current vaccination and vaccination in the previous season provided similar levels of protection; Vaccination-induced protection was greatest for individuals not vaccinated in the previous 5 years. The authors also concluded that more research is needed to understand the long-term effects of annual vaccination.

It cannot be excluded that vaccination in the previous season may reduce the effectiveness of the current season's vaccine, in particular for A(H3N2). However, the positive results among those vaccinated only in the current season and those vaccinated in both seasons obtained in the M. Valenciano study

E. Kissling, A. Larrauri et al. suggest that vaccination in a certain season is always beneficial [27]. To monitor the effectiveness of influenza vaccine in the European Union (EU) and the European Economic Area (EEA), the Influenza Vaccination Monitoring Network for Europe, I-MOVE, was established in 2007 [28]. The network is funded by the European Center for Disease Prevention and Control (ECDC) and includes 19 public health institutes from the EU and EEA. Despite the growing sample size in I-MOVE, results are still imprecise due to low vaccination coverage and the strong association between current season vaccination and previous season vaccination. The effectiveness of influenza vaccine depends on complex interactions between the individual, the viral agent, and environmental factors. To optimally measure and interpret the seasonal effectiveness of influenza vaccines, it would be necessary to consider multiple parameters, including virus subtypes, clades, subclades, age of vaccine recipients, health status at the time of vaccination, time of vaccination initiation, duration of protection, vaccine types and brands, natural immunity, and previous vaccinations. Only long-term prospective studies will provide insight into the immunological response to influenza vaccinations and the occurrence of infection.

Monitoring the circulation of influenza viruses

Another equally important task, the solution of which determines the effectiveness of influenza vaccines, is monitoring the circulation of influenza viruses for the timely inclusion of modern current strains in the vaccines.

Application of quadrivaccines

Due to the constantly changing nature of influenza viruses, the WHO Global Influenza Surveillance and Response System (GISRS) - a system of national influenza centers and WHO collaborating centers around the world - has been continuously monitoring influenza viruses circulating in humans for many years and updating its recommendations regarding the composition of the vaccine. Since the late 1970s. in the human community, simultaneous circulation of viruses A and B is recorded. This became the basis for recommendations for the inclusion of these three strains in seasonal influenza vaccines - two subtypes of influenza A virus and one subtype of influenza B virus. Since the second half of the 1980s. Experts began to identify two antigenically different phylogenetic lineages of the B virus strain - Victorian and Yamagata, which circulated in different seasons or simultaneously during the same epidemic period. At the same time, only one strain B was included in the vaccines, which did not always coincide with the seasonal one. In such seasons, vaccine strain B did not provide complete protection against the wild strain of another line, and this led to a decrease in the effectiveness of vaccination. The impossibility of accurately predicting which strain of the B virus will prevail in the upcoming epidemic season in a particular territory, combined with data from monitoring seasonal epidemics, confirmed the need to include two strains of influenza virus type B in the vaccine and became the basis for the creation of quadrivalent influenza vaccines - quadrivaccin.

Since the 2012–2013 influenza season. In the Northern Hemisphere, it is recommended that a fourth influenza B virus component be added to trivalent vaccines to provide broader protection against influenza B virus infections in both lineages. The first quadrivalent vaccine appeared on the European market in 2012; later quadrivalent vaccines were registered in the USA, Canada, Australia, and China.

A randomized, multicenter, phase III trial was conducted in Europe from September 2014 to October 2015 to evaluate the immunogenicity and safety of quadrivalent inactivated split vaccine compared with trivalent IVIG in young and older adults [29]. The study pooled results from 15 European influenza centres: three in Belgium, three in France, four in Germany and five in Poland. A total of 2125 people were under observation, of which 1114 were aged 18–60 years, 1111 people were over 60 years old. In accordance with WHO and EU recommendations for the 2014–2015 influenza epidemic season. in the Northern Hemisphere, the following vaccines were used: quadrivalent IIV - Vaxigrip Tetra (Sanofi Pasteur, Lyon, France), which included strains A/California/7/2009 pdm09(H1N1), A/Texas/50/2012 (H3N2), B /Brisbane/60/2008 Victorian Line and B/Massachusetts/2/2012 Yamagata Line; trivalent IVH, containing the above two A strains and a Victorian strain; trivalent IVH containing the two above-mentioned A strains and a strain of the Yamagata line. All vaccines were free from thiomersal, each dose of the vaccine (0.5 ml) contained 15 μg of hemagglutinin of each strain. The study found that in both younger and older adults, the quadrivalent vaccine had a safety profile similar to that of the licensed trivalent vaccine. The inclusion of a second strain B ensured the formation of antibodies at a sufficiently high level without affecting the immunogenicity of the other three strains. The vaccine provided good protection even to people at high risk of influenza and to people vaccinated last year against seasonal influenza.

Evaluation of the effectiveness of quadrivalent domestic influenza vaccines

In 2016–2017 In Russia, a clinical double-blind randomized study was conducted that assessed the tolerability, safety and immunogenicity of the domestic quadrivalent subunit vaccine Grippol® Quadrivalent (NPO Petrovax Pharm LLC), containing 5 μg of antigens of 2 influenza A viruses - A/California/7/ 2009pdm (H1N1), A/Hong Kong/4801/2014(H3N2), and 2 influenza B viruses – B/Brisbane/60/2008 and B/Phuket/3073/2013, compared with trivalent Grippol® plus vaccines containing influenza virus antigens A (H1N1 and H3N2) and one type B virus of the Victorian or Yamagata lineages, in 600 volunteers aged 18–60 years [30]. The study showed that the Grippol® Quadrivalent vaccine meets the EMA CPMP criteria; has a high tolerability and safety profile [31]. In Russia, the Grippol® Quadri-valent vaccine was registered in 2022.

In 2022, the Ultrix QUADRI vaccine (Fort LLC) was registered in Russia, used for immunization of the population in the 2019–2020 season.

The creation and implementation of quadrivalent domestic influenza vaccines into healthcare practice will further increase the effectiveness of vaccination and significantly increase the economic effect of this preventive measure.

Conclusion

In conclusion, we should once again emphasize the importance of analyzing data from long-term monitoring of the effectiveness of domestic influenza vaccines, which will allow us to develop a number of scientifically based measures aimed at reducing morbidity, hospitalization and mortality from influenza through a more rational use of different types of influenza vaccines in relation to different age categories of the population .

What complications can occur after vaccinations?

• allergic reaction, if you are allergic to chicken protein, you should inform your doctor;
• the occurrence of a local reaction at the site of vaccine administration;
• after vaccination, symptoms of acute respiratory viral infection or flu may appear, but they are usually more easily tolerated than if an infection had occurred with an unattenuated virus.

From September to October 2022, you can get vaccinated under the compulsory medical insurance policy at your place of attachment or go to a private clinic. The average cost of vaccination is about 500 rubles.

There are contraindications. Specialist consultation is required.

Early 20th century: Spanish flu

The most famous flu pandemic that everyone hears is the Spanish flu. It is not known for certain where the pandemic began. It is believed that China was among the first countries. A little later - America and France, and only a few months later - Spain, Italy, Switzerland and then the whole world.

The Spanish flu is a flu, its pandemic lasted two years (1918-1920), about 30% of the planet's population (about 550 million people) became infected, and up to 50-100 million people died.

A distinctive feature of the disease was the rapid development of severe pneumonia. The Spanish flu claimed the lives of the younger generation, almost without affecting people 50-60 years old. Later, medicine will explain this mystery by the fact that the older generation had already developed immunity due to previously suffering from influenza with similar strains.

In those days, doctors were almost powerless. They looked for various methods of treatment, but the only thing that somehow helped was blood transfusions from those who had already been ill and recovered.

Mid-20th century: the secret of the virus revealed

By this time, scientists had already identified 3 types of influenza virus. They are designated A, B and C.

1957 American virologist, Maurice Hilleman and his colleagues, when discovering the next type of influenza virus, discovered that people who survived the 1889-1890 pandemic were resistant to the new virus. Scientists have identified which proteins are responsible for the formation of immunity and have developed a suitable vaccine.

It turned out that the influenza virus consists of surface

and
internal
antigens. Surface antigens are variable, but internal antigens are constant.

Surface antigens

– this is:
hemagglutinin
(in the name of the strain it is designated H) – ensures the ability of the virus to attach to the cell;
neuraminidase
(denoted N) - is responsible for the ability of a viral particle to penetrate the host cell and for the ability of viral particles to exit the cell after reproduction.

Both hemagglutinin and neuraminidase have varieties that are usually numbered: H1, H2, H3..., N1, N2, N3... The high variability of the influenza virus type “A” is due to two properties: A) the possibility of gene exchange between different viruses during simultaneous infection of the same and the same cells, and B) gradual variability in the structure of N and H as a result of mutations (antigenic drift).

Combinations of different surface antigens determine different strains of the same A virus (H1N5, H1N1, etc.). One of the most recently identified H18N11 strains was found in 2013 in bats in Central America.

Internal antigens

make up the core (genome) of the virus in the form of
a ribonucleoprotein complex (nucleoprotein in complex with viral RNA)
and determine the type of virus (A, B or C).

When the secret of the virus was revealed, 40 million doses were produced, which helped reduce the number of deaths in the United States tenfold. In 1968, Hilleman was given another strain, the Hong Kong flu, and four months later another new vaccine was produced.

However, countries without a vaccine continued to suffer from the return of the virus, with outbreaks recorded in late 1969, 1970 and 1972. However, there were no such devastating consequences, because by this time there were antibiotics that saved from secondary infections; there was vaccination in a number of states; and many who have recovered have developed immunity.

Why doesn't the vaccine protect 100%?

Previously, we have already examined cases when vaccinated people can also get sick. Once again, we note that any vaccines do not provide a 100% guarantee. In the instructions for the drugs you will see efficiency indicators that are always above 80%, close to 95-99%.

Efficacy is influenced by the initial characteristics of the vaccine and the immune status of the individual. In the case of influenza, we described the additional risks and complexities associated with yearly forecasting and updating of strains.

Scientists have extensive experience in combating this elusive enemy; more than 2,000 serotypes of influenza viruses are known in the world. However, the risk of a completely new mutation always exists, and scientists cannot yet control this. Just like they cannot create a vaccine that would protect against influenza for life and 100%.

Whether you should get vaccinated when you are unsure of the Global Influenza Surveillance System forecasts is up to you. Perhaps the numbers will help you make a difficult choice: in Russia, among those sick with influenza A, 91.8% were unvaccinated, and among those who died, 100%.

The end of the 20th – the beginning of the 21st centuries: by surprise

No matter how well GISRS works, unfortunately, sometimes the virus manages to break through contrary to scientists’ predictions. Humanity was taken by surprise by the outbreaks of the so-called “bird” and “swine” flu at the beginning of the 21st century. These strains, a recombination of human and animal viruses (birds and pigs), turned out to be completely new to human immunity and were not included in the WHO forecast.

In such rare cases, when unexpected mutations of influenza occur, vaccines are created on an emergency basis to prevent the infection from spreading widely, and are used separately, or the new strain is included in the seasonal vaccine.

In general, over the almost 70 years of existence of GISRS, the system has proven itself to be excellent and has shown the correctness of the adopted strategy for the prevention of influenza by adapting vaccine production to virus mutations.

To summarize the historical excursion, I would like to note the contribution of vaccination to protecting the population from influenza. According to the State report “On the state of sanitary and epidemiological well-being of the population in the Russian Federation in 2022”, the effectiveness of vaccination is clearly confirmed by the dynamics of influenza incidence, the level of which has decreased by almost 140 times since 1997 (from 5173.8 per 100 thousand population (with vaccination coverage of 4.9 million people in 1996) to 37.3 in 2022 (with vaccination coverage of 70.8 million people in 2022).

The graph clearly shows a decrease in incidence in direct proportion to the number of people vaccinated: