Influenza vaccination in children and adults: contraindications

The flu vaccine has only been included in the National Calendar since 2006. In European countries, a complete record of flu cases is kept, and although it is far from complete, the flu vaccine has led to a decrease in the incidence of the disease.

According to WHO, 5-10% of adults and 20-30% of children fall ill with the annual flu epidemics; 250,000-500,000 people die from this disease worldwide, and the economic damage ranges from 1 to 6 million dollars per 100,000 population.

The flu vaccine should be administered to chronically ill patients, those who often suffer from acute respiratory infections, and preschool-aged children. In European countries, the elderly, patients with cardiac, pulmonary (including bronchial asthma) and renal pathology, diabetes, and also people with immunosuppression are vaccinated. In the USA, since 2008, the flu vaccine for those over 6 months has been included in the National Calendar.

Flu vaccination for children

Influenza vaccination should be carried out already in the first year, since at this age there is a high incidence of the disease and a severe course of the disease. Thus, in the 2007/08 season, the proportion of children aged 0-2 years among those sick with influenza was 38.4%, 3-6 years - 43.5%, while schoolchildren were only 14%, and adults - 2.8%. Among children hospitalized with confirmed influenza, 50% were children under 6 months, 2/3 were children under 1 year, and 80% were under 2 years. Another study showed that of children aged 2-5 years who fell ill with influenza, every 250th was hospitalized, 6-24 months - every 100th. and 0-6 months. - every 10th. According to the consolidated data of the American Academy of Pediatrics, the frequency of hospitalization for this disease is 240-720 per 100,000 children 0-6 months and 17-45 per 100,000 children 2-5 years old; 37% of those hospitalized belonged to the risk group - their hospitalization frequency is 500 per 100,000.

And although the mortality rate of children is 1/10 of the mortality rate of elderly people (0.1 and 1.0 per 100,000), a special study of this issue in the USA in 2004-2005 showed that for children in the first half of the year this figure is 0.88 per 100,000.

Symptoms of influenza in young children often differ from the classic picture - high fever + intoxication + cough and runny nose. At this age, against the background of high temperature, febrile seizures are not uncommon, influenza often causes croup, bronchiolitis, exacerbation of asthma, is often complicated by otitis media, sinusitis and pneumonia. The frequency of otitis in children with influenza is 18-40% according to various studies, much more often in children under 2 years old. Complications with myocarditis, as well as from the nervous system, are not uncommon. Thus, in one study of 842 children with laboratory-confirmed influenza, 72 had neurological complications: encephalopathy in 10 children, febrile seizures in 27 and afebrile - in 29, meningitis in 2 and cerebral stroke due to hypotension - in 4.

Who should get vaccinated?

The contingent specified in the National Calendar does not include a number of groups, the flu vaccination of which gives an undoubted effect and can be recommended; The calendar of immunoprophylaxis according to epidemiological indications does not decipher risk groups. The recommendations in force in the USA are presented below, the flu vaccination should be carried out for the following categories of people:

• Healthy children over 6 months of age.
• Asthma and other chronic lung diseases such as cystic fibrosis.
• Heart diseases with hemodynamic disturbances.
• Conditions that can lead to respiratory dysfunction (aspiration, sputum retention) - epilepsy, neuromuscular diseases, spinal cord injuries, mental retardation
• Immunodeficiencies, including HIV infection.
• Sickle cell anemia and other hemoglobinopathies.
• Chronic kidney disease, metabolic disease, diabetes mellitus,
• Diseases requiring long-term therapy with acetylsalicylic acid (rheumatic diseases, Kawasaki syndrome) as a prevention of Reye's syndrome.
• Family members and staff caring for children under 5 years of age (especially important for children under 6 months of age)

These recommendations, although they do not include such obvious risk groups as patients with organic lesions of the central nervous system, in whom influenza causes prolonged apnea, children with lung malformations and bronchopulmonary dysplasia, are quite acceptable for our conditions. Of course, we should also recommend vaccination on an individual basis to all children and adults.

Flu vaccination is safe for people with chronic diseases. There are enough convincing studies published that allow these groups to be safely vaccinated.

Flu vaccines

The flu vaccine is prepared from the current strains of the A/H1N1/, A/H3N2/ and B viruses, recommended annually by WHO. The flu vaccination is carried out in the fall, preferably before the onset of an increase in the incidence of the disease.

Instead of the previously produced anti-influenza gamma globulin, normal human immunoglobulin is used in double the dosage.

A flu vaccine is currently being tested that is based not on hemagglutinin and neuraminidase, but on matrix protein 1 and virion nucleoprotein, which do not mutate; if successful, this would eliminate the need for annual vaccinations.

Live vaccines are made from attenuated strains of the virus (cold-adapted mutants) and are capable of producing local immunity (production of IgA antibodies) when administered intranasally. In the United States, where the live vaccine is used from the age of 5, including in children with asthma, its higher efficacy has been demonstrated compared to the inactivated vaccine against A/H1N1 and B.

Influenza vaccine allantoic intranasal live dry for children from 3 years and adults (Microgen, Russia) - lyophilisate for solution preparation. The contents of the ampoule are dissolved in 0.5 ml (1 dose) of boiled water (cooled). The age-appropriate vaccine is administered once at 0.25 ml in each nasal passage to a depth of 0.5 cm with the supplied disposable sprayer-dispenser type RD.

The flu vaccine is weakly reactogenic. The preparations should be stored at a temperature of 2 to 8. The shelf life is 1 year.

Inactivated whole-virion flu vaccine is used in children over 7 years of age and adults. It consists of purified viruses cultured on chicken embryos and inactivated by UV irradiation.

Grippovac (NIIVS, Russia) contains 20 mcg of hemagglutinin subtypes A and 26 mcg of B per 1 ml. Preservative - thimerosal. Release form: ampoules of 1 ml (2 doses), vials of 40 or 100 doses. Store at 2-8 °. It is administered to children from 7 years of age and adolescents intranasally (with an RJ-M4 nebulizer) 0.25 ml in each nasal passage twice with an interval of 3-4 weeks, to adults - from 18 years of age - intranasally according to the same scheme or parenterally (s/c) once at a dose of 0.5 ml.

Flu vaccine inactivated eluate-centrifugal liquid (Russia) - used according to the same scheme as Grippovac

Subunit and split vaccines are used in children over 6 months, adolescents and adults. Children vaccinated for the first time and who have not had influenza, as well as patients with immunodeficiency, are recommended to be administered 2 doses at intervals of 4 weeks, in subsequent years - once. When administered 1 dose in the spring and one in the fall, the vaccines are less immunogenic.

The flu vaccine is administered intramuscularly or deeply subcutaneously into the upper third of the outer surface of the shoulder. Vaccines are stored at 2-8°. The shelf life is 12-18 months.

Subunit and split vaccines registered in Russia

Flu shot	Composition, preservative	Doses and vaccination methods
Grippol Subunit-Microgen, Russia	5 mcg of 2 strains A and 11 mcg of strain B, + polyoxidonium 500 mcg, thimerosal. Ampoules 0.5 ml	For children 6 months to 3 years old, 0.25 ml twice with an interval of 4 weeks; for children over 3 years old, 0.5 ml once.
Grippol® plus Polymer-subunit - FC Petrovax, Russia	5 mcg of 2 strains A and B (Solvay Biol.) + polyoxidonium 500 mcg, without preservative. Syringe, ampoules, 0.5 ml vials	Children over 3 years of age and adults: 1 dose (0.5 ml) once
Agrippal S1 - Subunit, Novartis Vaccines and Diagnostics S.r.l, Italy	15 mcg 3 strains, without preservative. Syringe dose.	For children over 3 years of age and adults, 1 dose (0.5 ml) once, for children under 3 years of age - 1/2 dose (0.25 ml) - for those being vaccinated for the first time and who have not had the flu - 2 times after 1 month.
Begrivak Split, Nov Artis Vaccine, Germany	15 mcg 3 strains, preservative free. Syringe dose
Vaxigrip Split, Sanofi Pasteur, France	15 mcg of 3 strains, without preservative. Syringe doses, 0.5 ml ampoules, 10 dose vials	For children under 9 years old, 2 times, 0.25 ml (up to 3 years) or 0.5 ml (3-8 years); >9 years - 1 dose of 0.5 ml.
Inflexal V Subunit, Berna Biotech, Switzerland	15 mcg of 3 strains; virosomes mimic the virion. Without preservatives, formaldehyde and antibiotics	For children over 3 years old and adults - 0.5 ml intramuscularly or deeply subcutaneously, for children from 6 months to 3 years old - 0.25 ml (for those not previously vaccinated - 2 doses).
Influvac Subunit, Solvay Pharma, The Netherlands	15 mcg 3 strains, No preservatives or antibiotics. Self-destructing syringe dose.	Persons >14 years 0.5 ml. Children <3 years - 0.25 ml, 3-14 years - 0.5 ml, those who have not been ill or vaccinated before - 2 times. Vaccination of pregnant women is permitted.
Fluarix Split, SmithKlineBeachamForm. GmbH, KG, Germany	15 mcg 3 strains, traces of thimerosal and formaldehyde. Syringe dose.	Children over 6 years old - 0.5 ml once, 6 months - 6 years - 0.25 ml 2 times

The cell culture-grown subunit influenza vaccine On-taflu, Novartis Vaccine and Diagnostics GmbH, Germany, and the split vaccine FluvaxN, ChangchukLife Science Ltd., China, are being registered.

The flu vaccine is not active against bird flu viruses and its possible future mutants. In Russia and other countries, vaccines have been created from "bird" strains in case of an epidemic.

Contraindications to flu vaccination

For all vaccines - allergy to chicken egg proteins, to aminoglycosides (for vaccines containing them), allergic reactions to the introduction of any vaccine. Split and subunit flu vaccination can be used in people with chronic pathology, including immune deficiencies, pregnant and lactating women, patients on immunosuppressive therapy, combined with other vaccines (in different syringes). It is not recommended to vaccinate people who have had Guillain-Barré syndrome.

Contraindications for live vaccines are immunodeficiency states, immunosuppression, malignant neoplasms, rhinitis, pregnancy, intolerance to chicken protein. Temporary contraindications, as for inactivated vaccines, are acute diseases and exacerbations of chronic ones.

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Vaccination reactions and complications

Live flu vaccination is weakly reactogenic, temperature above 37.5° in the first 3 days is allowed in no more than 2% of vaccinated persons. With subcutaneous administration of whole-cell vaccines, short-term temperature above 37.5° or infiltrates up to 50 mm are allowed in no more than 3% of vaccinated persons. With their intranasal administration, subfebrile temperature for 1-3 days is allowed in no more than 2% of vaccinated persons.

Subunit and split vaccines produce weak short-term (48-72 hours) reactions in no more than 3% of those vaccinated. According to international independent studies, subunit vaccines are the least reactogenic. Clinical experience confirms the low reactogenicity of inactivated sipit- and subunit vaccines even in children in the second half of life. The largest amount of material (about 70,000 doses) on vaccine safety comes from the USA. There are also observations that the flu vaccine is safe for children in the first half of the year.

Rare cases of vasculitis have been described. Observations in England of 34,000 people vaccinated with different vaccines (including 75% with chronic pathology) showed a low frequency of both all and allergic reactions (in total within 1-3% for different vaccines).

Rare immediate reactions after the Grippol flu vaccine was administered in 2006 have virtually never been repeated.

Is the flu shot effective?

The flu vaccine develops immunity 14 days after the injection, but in children who have not previously had contact with the virus, this requires 2 doses of the vaccine, administered at intervals of 4-6 weeks. Immunity is type-specific; The flu vaccine should be administered every year, since there is antigenic drift of virus strains, as well as its short duration (6-12 months), even if its strain composition has not changed compared to the previous season.

The flu vaccine has a preventive efficacy of 60-90% against laboratory-confirmed disease, although the level of protection in children and the elderly is considered lower. When infected with strains of the virus that differ from those in the vaccine, the efficacy decreases; although the disease is milder in vaccinated people, the incidence of influenza and mortality remain above the epidemic threshold.

Influenza vaccination is the most effective method of reducing influenza incidence and mortality both in the general population and in risk groups. Influenza vaccination reduces hospitalization of children aged 6-23 months (who received 2 doses of the vaccine) by 75%, and mortality by 41%, and the protective effect of vaccination administered for 2 years or more is much higher than a single dose before the epidemic. Among adults with community-acquired pneumonia vaccinated against influenza, mortality was lower during the influenza season - OR 0.3 (0.22-0.41). The effect is especially pronounced among the elderly: over 10 seasons, the relative risk of pneumonia was 0.73 and death - 0.52.

Flu vaccination also reduces the incidence of acute otitis media (by 2.3-5.2%) and exudative otitis (by 22.8-31.1%) in children. Flu vaccination reduces the incidence of all acute respiratory infections.

To protect children in the first half of the year from this disease, the effect of vaccination of pregnant women is being studied. Data from Bangladesh showed that such a flu shot has an efficiency of 63%: up to the age of 24 weeks, 4% of children fell ill with confirmed flu against 10% in the control group. In addition, the frequency of febrile ARI decreased by 29%.

The problem of bird flu

The highly pathogenic avian influenza virus (H5N1) multiplies in the intestines of birds - its N1 neuraminidase is resistant to an acidic environment, and the H5 hemagglutinin recognizes epithelial receptors containing sialic acids, which are typical for birds. Humans have few such receptors (that is why people rarely get sick), but the trachea of pigs contains both types of sialic acids, which makes them the main "mixer" of viruses. Mass transmission from person to person is possible only if the specificity of the hemagglutinin of the avian virus changes.

Post-exposure prophylaxis

The flu vaccination should be done before the start of the cold season. During the epidemic, interferon-a is used - nasal drops Alfaron, Grippferon (10,000 units/ml) and in aeosols: for children 0-1 year old, 1 drop (1,000 IU); 1-14 years old - 2, over 14 years old and adults - 3 drops 2 times a day for 5-7 days (upon contact with a patient with the flu) or an age-related dose in the morning every 1-2 days (during the epidemic season). Viferon 1 suppositories are used according to the same scheme. Interferon-gamma (Ingaron - 100,000 IU in a bottle, diluted in 5 liters of water) for children over 7 years old and adults, 2 drops in the nose: in case of contact with a patient with the flu - once, during the epidemic season - 2-3 drops 30 minutes before meals after washing the nose once every other day for 10 days (repeat course if necessary - after 2 weeks).

For prophylaxis in adults and children over 1 year old, rimantadine is used (50 mg tablets, 2% syrup for children Algirem with sodium alginate), although the A1 virus has acquired resistance to it. Rimantadine doses: 100 mg / day (children 7-10 years old), 150 mg / day (children over 10 years old and adults); Algirem: children 1-3 years old 10 ml (20 mg) children 3-7 years old - 15 ml: (30 mg) - 1 time per day for 10-15 days. Arbidol has a similar effect - according to the same scheme: children 2-6 years old - 0.05, 6-12 years old - 0.1, over 12 years old - 0.2 g.

The neuraminidase inhibitor oseltamivir (Tamiflu) is approved for the treatment and prevention of influenza A and B from 1 year. When used within 36 hours after contact with a patient, it prevents influenza in 80%, and is active against bird flu (but not against acute respiratory viral infections). The prophylactic dose for children is 1-2 mg/kg/day, for adults - 75-150 mg/day - 7 days after contact or up to 6 weeks during an epidemic. Zanamivir (Relenza in an aerosol is used starting from the age of 5 years, 2 inhalations 2 times a day (total 10 mg/day) for treatment and prevention.

Flu vaccination for people with chronic diseases

The flu vaccine in the form of split and subunit vaccines has proven its effectiveness and safety when administered to patients with serious pathologies (asthma, leukemia, liver transplant recipients, diabetes, multiple sclerosis, etc.). Clinical experience of vaccinating more than 5,000 children, including 31 with various pathologies, has shown its safety and effectiveness.