Comparative assessment of the tolerability, safety, and immunogenicity of the FLU-M® Tetra quadrivalent inactivated split influenza vaccine and the Ultrix® vaccine in volunteers aged 60 years and above.

Evaluation of the tolerability, safety and immunogenicity of the inactivated split influenza vaccine FLU-M® Tetra compared to Ultrix® vaccine in volunteers aged 60 years and above.

Volunteers were screened and randomized in three groups: the Flu-M Tetra w/p (with preservative) group, the Flu-M Tetra w/o/p (without preservative) group and the Ultrix® group. All subjects were followed up for 28 days post randomization and vaccination.

Inclusion Criteria:

1. Volunteers (men and women) at the age of 60 years and above
2. Written informed consent of volunteers to participate in the clinical trial;
3. Volunteers able to fulfill requirements of the Protocol (i.e. fill out the patient's diary, come to follow-up visits);
4. For fertile women - a negative result of the pregnancy test and consent to observe adequate methods of contraception during the trial and at least two months after vaccination;
5. For fertile men - consent to observe adequate methods of contraception during the trial and at least two months after vaccination, except for men after vasectomy with documented azoospermia, and their sexual partners should use methods of contraception that ensure more than 90% reliability or be incapable of conception after a surgical sterilization or have a natural menopause for at least 2 years.

Exclusion Criteria:

1. History of influenza/ARVI or previous influenza vaccination during 6 months before the trial;
2. Positive result of the SARS-CoV-2 test;
3. A serious post-vaccination reaction (temperature above 40 °C, hyperemia or edema more than 8 cm in diameter) 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);
4. Allergic reactions to vaccine components or any previous vaccination;
5. History of allergic reaction to chicken protein;
6. History of Guillain-Barré syndrome (acute polyneuropathy);
7. Previous vaccination with rabies vaccines less than 2 months before immunization or scheduled vaccination with rabies vaccines within 1 month after immunization with the trial vaccines;
8. History of leukemia, cancer, autoimmune diseases;
9. Positive blood test results for HIV, syphilis, hepatitis B/C.
10. Volunteers who received immunoglobulin or blood products or had a blood transfusion during the last three months before the trial;
11. History of long-term use (more than 14 days) of immunosuppressants or immunomodulatory drugs for six months before the trial;
12. History of any confirmed or suspected immunosuppressive or immunodeficiency condition;
13. History of chronic diseases of the cardiovascular, bronchopulmonary, neuroendocrine systems, the gastrointestinal tract, liver, kidneys, hematopoietic, immune and endocrine system, mental disease in the acute stage or in the decompensation stage (recovery less than 4 weeks before vaccination);
14. History of eczema;
15. Treatment with glucocorticosteroids, including in small doses, as well as local use of drugs containing steroids (> 10 mg of prednisolone or its equivalent for more than 14 days before the screening);
16. Tuberculosis, neurological or mental disorders, a convulsive syndrome, including in the past medical history;
17. History of acute infectious diseases (recovery less than 4 weeks before vaccination);
18. Consumption of more than 10 units of alcohol per week or history of alcohol addiction, drug addiction or abuse of pharmaceutical products;
19. Smoking of more than 10 cigarettes per day;
20. Participation in another clinical trial during the last 3 months;
21. Pregnancy or lactation;
22. Coagulopathy, haemophilia;
23. Taking aspirin or other antiplatelet agents in high doses.