The pivotal Phase 3 trial plans to enroll a total of approximately 12,460 participants aged 50+ over two years. Participants will be immunized twice with the M-001 universal influenza vaccine candidate or placebo and then followed for up to 2 seasons. The trial will evaluate the number of influenza cases in each group and the severity of illness during the follow up period.

The placebo-controlled pivotal clinical efficacy Phase 3 trial plans to enroll a total of approximately 12,460 participants over two years. Participants will be immunized twice with the M-001 influenza vaccine candidate or placebo. Influenza incidence and illness severity will be evaluated throughout the follow-up period of up to two years. Participants will be 50 years and older, with at least half over 65 years of age.

The trial is expected to take place in eastern European countries and begin prior to the 2018/19 Northern Hemisphere flu season.

Inclusion Criteria:

1. Male and female subjects 50 years of age (inclusive) or older, mentally competent, willing and able to give the written informed consent prior to study entry
2. Able to comply with the trial procedures and be available for all study visits.
3. Medically stable. (Subjects may have underlying chronic conditions such as hypertension, diabetes, ischemic heart disease, or hypothyroidism, as long as their symptoms/signs are controlled. If they are on medication for a condition, the medication dose must have been stable for at least 3 months preceding vaccination).
4. Women of childbearing potential (not surgically sterile or postmenopausal for greater than or equal to one year) and men must agree to practice adequate contraception (barrier or hormone methods or intra uterine device (IUD) for women and a condom for men) throughout the study treatment and for at least up to day 51 (for female) and day 111 (for male) of the trial (i.e. 30 (for female) and 90 (for male) days after the last dose of the IMP)
5. Female subjects of childbearing potential must have a negative urine or serum pregnancy test within 24 hours prior to study vaccination.

Exclusion Criteria:

1. History of neurological symptoms or signs, or anaphylactic shock following administration of any vaccine.
2. Known or suspected (or have a high risk of developing) impairment/alteration of immune function (excluding that normally associated with advanced age).
3. Receipt of: a) Immunosuppressive drugs: i) systemic glucocorticoids >/= 10 mg prednisone per day ii) cytotoxic drugs b) Investigational drugs within 30 days before, or planned during, the study c) Blood products within 3 months before, or planned during, the study d) Influenza vaccine within 6 months before the study) Other vaccines within 30 days before, or planned during, the study
4. Any serious disease such as: cancer, autoimmune disease, advanced arteriosclerotic disease or complicated diabetes mellitus, chronic obstructive pulmonary disease (COPD) that requires oxygen therapy, acute or progressive hepatic disease, acute or progressive renal disease, or congestive heart failure, as judged by the PI.
5. An acute illness, including an axillary temperature greater than 38 Celsius (38ºC), occurred within 1 week before first vaccination
6. Positive positive urine pregnancy test prior to vaccination or women who are breastfeeding.

Baseline analysis population is the Intention-to-treat population, i.e. subjects who received at least one vaccination

4 months

All parties are blinded except for the person who prepares the syringe for injection. The M-001 is cloudy white and its appearance is different from the transparent saline that is used for placebo. The person prepares the syringe with an opaque sticker that fully covers the syringe contents. People administering the syringe are not involved or present during syringe preparation, and are thus fully blinded.