Comparative trial of tolerability, reactogenicity, safety and immunogenicity of the Flu-M vaccine as compared to the Vaxigrip® vaccine in terms of prevention of influenza in children aged 6 months to 9 years (at the time of the first vaccination).

The trial includes 2 stages (stage I, II). At stage I children aged 3-9 years will be included. Based on findings from tolerability and safety assessment in respect of the Flu-M vaccine vs. the Vaxigrip® vaccine for the first 7 days after vaccination of volunteers during Stage I, an intermediate report will be prepared. The report will be submitted to the supervisory executive authorities alongside the notice of commencement of Stage II of the trial - the continuation of trial on children aged 3-9 years and the commencement of trial on children aged between 6 months and 35 months. During Stage II, the trial for Stage I volunteers will continue in full and also children aged between 6 and 35 months will be included in the trial.

Inclusion Criteria:

• For volunteers aged 3 to 9 years:

  • Healthy children of both sexes aged 3 to 9 years (3 years 0 months 0 days - 8 years 11 months 30 days);
  • The written and dated informed consent of one of the parents for participation in the trial;

• For volunteers aged 6 to 35 months:

  • Healthy children of both genders aged 6 to 35 months, inclusive (6 months 0 days - 35 months 30 days);
  • The written and dated informed consent of one of the parents for participation in the trial;
  • The trial subject of the was born full-term, with the Apgar score of 7-10 points.

• For all volunteers:

Ability of a volunteer's parents to fulfill the requirements of the Protocol (i.e. to fill out the Patient Diary, come to visit with the volunteer).

Exclusion Criteria:

1. History of influenza (including in mothers for children aged 6 to 35 months) or previous influenza vaccination during 6 months before the trial;
2. Positive result of the SARS-CoV-2 test;
3. Vaccination of the pregnant woman in the 2nd-3rd trimester (for the age group of 6 - 35 months) with an influenza vaccine;
4. Vaccination with any vaccine less than 30 days before participating in the trial or scheduled vaccination with any vaccine within 30 days after vaccination with the trial vaccines;
5. A serious post-vaccination reaction (temperature above 40 °C, hyperemia or edema more than 8 cm in diameter at the injection site) or complications (collapse or shock-like condition that developed within 48 hours after vaccination; convulsions accompanied or not accompanied by a fever due to any previous vaccination), encephalopathy;
6. Allergic reactions to vaccine components or any previous vaccination;
7. History of allergic reaction to chicken protein;
8. History of cancer, leukemia, tuberculosis, autoimmune diseases;
9. Carriage of HIV, syphilis, hepatitis B and C in the medical history, including by parents;
10. Children who received immunoglobulin products or transfusions of whole blood or its components less than 3 months before the start of the trial;
11. Long-term use (more than 14 days) of any immunomodulating medicines less than 3 months before the start of the trial;
12. Any confirmed or suspected immunosuppressive or immunodeficiency condition;
13. History of chronic diseases of the cardiovascular, bronchopulmonary, endocrine systems, blood in the acute stage (recovery less than 4 weeks before vaccination) or in the decompensation stage;
14. Children with hemophilia who may develop bleeding after intramuscular injection;
15. History of progressive neurological pathology, convulsive syndrome, afebrile convulsions;
16. History of acute infectious diseases (fever ≥ 37.5°С): recovery less than 2 weeks before vaccination;
17. Participation in another clinical trial less than 3 months before the start of the trial;
18. History of mental illness of the child and the volunteer's parents;
19. The history of the volunteer's parent being registered with a tuberculosis dispensary and/or a narcological dispensary;
20. Maternal history of drug use or alcohol abuse during pregnancy and/or breastfeeding;
21. Pronounced congenital malformations in a child;
22. Suspected developmental delay in a child.