This is a follow-up of a previous dose-ranging study aimed at investigating 2 doses of the trivalent inactivated split virion influenza vaccine when administered by intradermal route with that of the current pharmaceutical presentation administered by intramuscular route.

Primary Objective:

To assess the immunogenicity of two pharmaceutical presentations of the trivalent inactivated split virion influenza vaccine 21 days after a single injection in subjects aged 18 to 57 years.

Secondary Objective:

To evaluate the safety profile during the 21-day period following each vaccination in each study group

This is an open (for the administration route) and double-blind (only for the two dosages administered at year 0 by using the investigational administration route) randomized trial conducted in subjects aged 18 to 60 years. The subjects will receive three vaccine injections at 1-year interval.

Inclusion Criteria :

• Subject aged between 18 and 57 years (i.e., less than 60 at the last vaccination)
• For woman of child-bearing potential, negative urine pregnancy test at V#01
• Use of effective contraception prior to and during the trial
• Subject available during the trial period
• Subject able to read and understand the informed consent form
• Informed consent form signed and dated by the subject prior to any protocol-required intervention (and Visit 05 and Visit 07, respectively).

Exclusion Criteria :

• Self-reported allergy to egg proteins, chick proteins, or any of the constituents of the vaccine, in particular, neomycin, formaldehyde, and octoxinol 9
• Acute febrile disease within the 72 hours preceding V#01, or axillary temperature >37.5°C the day of inclusion, prior to vaccination (>37.0°C Czech Republic)
• Subject with an aggravation of existing chronic illness (heart disease, respiratory disease, etc.)
• Vaccination against influenza within the 6 months preceding V#01
• Any vaccination within the 28 days preceding V#01 or scheduled between V#01 and V#02
• Breast-feeding
• Immunosuppressive therapy including long term systemic corticotherapy (20 mg/day of prednisolone or equivalent for >2 weeks) or cancer therapy within the month preceding V#01 or ongoing
• Immunoglobulin injection within the 3 months preceding V#01
• Subject taking part or planned to take part in another clinical trial (3 months before and through the trial duration)
• Subject having received extracted pituitary hormones
• Subjects who participated in the GID01 study (Lithuanian centers)