Assess Safety and Immunogenicity of A/H5 Inactivated Monovalent Influenza Vaccines at Different Antigen Dose Levels Adjuvanted With AS03 or MF59

1. Has an acute illness, as determined by the site investigator, within 72 hours prior to vaccination.

a. An acute illness that is nearly resolved, with only minor residual symptoms remaining, is allowable if, in the opinion of the site investigator, the residual symptoms will not interfere with the ability of study staff to assess safety parameters as required by the protocol.

2. Has a history of severe reaction to any influenza vaccine.

3. Has a known allergy to squalene-based adjuvants.

4. Female of childbearing potential who has a positive urine pregnancy test or who is currently breastfeeding.

5. Has a body mass index \>35 kg/m2 .

6. Has known human immunodeficiency virus, hepatitis B, or hepatitis C infection (based on medical history).

7. Has a history of any pIMDs (list provided in Protocol Appendix 3), neuralgia, paresthesia, neuritis, convulsions, or encephalomyelitis within 90 days prior to Screening, or a family history of Guillain-Barré syndrome.

8. Has narcolepsy or a first degree relative with narcolepsy.

9. Has a history of alcohol or drug abuse within 5 years prior to Screening.

10. Has any diagnosis, current or past, of schizophrenia, bipolar disease, or any other psychiatric diagnosis that may, in the opinion of the site investigator, interfere with participant compliance or safety evaluations.

11. Is immunosuppressed due to an underlying disease or medication, use of anticancer chemotherapy (cytotoxic), or radiation therapy.

12. With the exception of basal or squamous cell skin cancer, has known active neoplastic disease, including hematologic malignancy.

13. Has long-term use (≥14 consecutive days) of glucocorticoids including oral or parenteral prednisone or prednisone equivalent (\>20 mg total dose per day) or high-dose inhaled steroids (\>800 µg/day of beclomethasone dipropionate or equivalent) within 1 month prior to screening in this study. However, participants on low-dose inhaled steroids (≤800 µg/day of beclomethasone dipropionate or equivalent) or topical steroids are not excluded.

14. Has received immunoglobulin or other blood product (with the exception of Rho\[D\] immune globulin) within the 90 days prior to screening in this study.

15. Has received any (licensed or under Emergency Use Authorization \[EUA\]) live vaccines within 4 weeks or inactivated, messenger RNA (mRNA), or recombinant protein vaccines within 2 weeks prior to screening, or plans to receive such vaccines (including seasonal influenza and COVID-19 vaccines) from screening through 22 days following the second dose of the study vaccine, inclusive of the vaccination day (Screening Visit through Day 43).

16. Is participating or plans to participate in another interventional clinical trial (either active or follow-up phase) during the study period.

17. Has participated in an A(H5) influenza vaccine study in the past or has a history of A(H5) influenza infection prior to vaccination in this study. This includes, but is not limited to, influenza sub-types A(H5N1), A(H5N8), and A(H5N6).

18. Has any laboratory test result or clinical findings (including vital signs) that singly or in combination are likely to unfavorably alter the risks of participant participation or to confound study safety or immunogenicity results, in the opinion of the site investigator. Additionally, the following are exclusionary:

1. Alanine aminotransferase (ALT) or aspartate aminotransferase (AST) \>2 times the upper limit of normal (ULN), or

2. Bilirubin \>1.5 times the ULN unless isolated Gilbert's syndrome.

19. Has any disease or medical condition that, in the opinion of the site investigator, might confound interpretation of safety or immunogenicity.

What this study is about