Study to Evaluate Immunogenicity, Safety and Tolerability of Adjuvanted and Non-Adjuvanted H2N3 Influenza Vaccines in Adults

Inclusion Criteria:

• Individuals of 18 years of age and older on the day of informed consent who were notborn in 1968.

• Individuals who have voluntarily given written informed consent after the nature ofthe study has been explained according to local regulatory requirements, prior tostudy entry.

• Individuals who can comply with study procedures including follow-up.

• Males, females of non-childbearing potential or females of childbearing potentialwho are using an effective birth control method, at least 30 days prior to informedconsent, which they intend to use for at least 2 months after the last studyvaccination.

Exclusion Criteria:

• Females of childbearing potential who are pregnant, lactating, or who have notadhered to a specified set of contraceptive methods from at least 30 days prior tostudy entry and who do not plan to do so until 2 months after the last studyvaccination.

• A body mass index (BMI) ≥35 kg/m2.

• Progressive, unstable, or uncontrolled clinical conditions as per investigator'sassessment. Subjects must be stable and unchanged for a minimum of 3 months.

• Hypersensitivity, including allergy, to any component of vaccines, medicinalproducts or medical equipment whose use is foreseen in this study.

• Clinical conditions representing a contraindication to intramuscular vaccination andblood draws.

• Abnormal function of the immune system resulting from:

1. Clinical conditions.

2. Systemic administration of corticosteroids at a dose of ≥20 mg/day ofprednisone or equivalent for more than 14 consecutive days within 90 days priorto informed consent. Topical, inhaled and intranasal corticosteroids arepermitted. Intermittent use (one dose in 30 days) of intra-articularcorticosteroids are also permitted.

3. Administration of antineoplastic and immunomodulating agents or radiotherapywithin 90 days prior to informed consent.

• History of any medical condition considered an adverse event of special interest (AESI).

• Received immunoglobulins with immunomodulating effects or any blood products within 180 days prior to informed consent.

• Received an investigational or non-registered medicinal product within 30 days priorto informed consent.

• Study personnel or immediate family or household member of study personnel.

• Any other clinical condition that, in the opinion of the investigator, mightinterfere with the results of the study or pose additional risk to the subject dueto participation in the study.

• Individuals who received any other vaccines (with the exception of COVID-19vaccines) within 14 days (for inactivated vaccines) or 28 days (for live vaccines)prior to enrolment in this study or who are planning to receive any vaccine within 28 days from the study vaccines.

• Receipt of any (investigational or licensed) COVID-19 vaccine within 14 days (non-replicating vaccines) or 28 days (replicating vaccines) prior to enrollment orplan to receive any COVID-19 vaccine within 14 days from study vaccination.

• A known history of Guillain-Barre Syndrome or other demyelinating diseases such asencephalomyelitis and transverse myelitis.