This clinical study will assess the safety, tolerability and immunogenicity of VAL-339851 in healthy subjects.

Inclusion Criteria:

• Agrees to comply with the study procedures and provides written informed consent
• 18 to 49 years of age
• Body mass index between 18 and 35 kg/m2
• Negative urine pregnancy test at the Screening visit and the day of each vaccination for females of childbearing potential.
• Female subjects must either be of non-childbearing potential or use acceptable methods of contraception from at least 3 weeks prior to enrollment and through the end of study visit
• In good health based on medical history, physical examination, vital sign measurements and laboratory safety tests performed prior to initial study vaccination
• Has access to a consistent and reliable means of telephone contact and agrees to stay in contact with the study site for the duration of the study

Exclusion Criteria:

• Any ongoing, symptomatic acute or chronic illness requiring medical or surgical care
• Administration of another investigational product within 60 days, or 5 half-lives, whichever is longer
• Participation in an investigational study involving lipid nanoparticles
• A history of hypersensitivity or serious reactions to previous influenza vaccinations
• History of Guillain-Barré Syndrome within 6 weeks following a previous influenza vaccine
• History of narcolepsy
• Administration of any licensed (inactivated or live) vaccines within 4 weeks before enrollment or plans to receive any vaccine within 12 weeks of the last study drug administration; receipt of any other avian H7N9 influenza vaccine at any time prior to or during the study is exclusionary
• Any known or suspected immunosuppressive condition, acquired or congenital, as determined by history and/or physical examination.
• Any chronic administration of immunosuppressant or other immune-modifying drugs within 6 months prior to administration of study vaccine
• Administration of immunoglobulins and/or any blood products within the 3 months preceding the administration of the study vaccine or during the study.
• Any acute disease at the time of enrollment
• Any significant disorder of coagulation requiring ongoing or intermittent treatment
• Active neoplastic disease or a history of any hematologic malignancy
• History of alcohol abuse or drug addiction within 1 year before the planned day of dose administration
• A positive test result for drugs of abuse or alcohol at screening or before the first dose administration
• Persons employed in a capacity that involves handling poultry or wild birds.
• The subject has any abnormality or permanent body art (eg, tattoo) that, in the opinion of the investigator, would obstruct the ability to observe local reactions at the injection site
• Any condition, that in the opinion of the Investigator would pose a health risk to the subject if enrolled or could interfere with evaluation of the vaccine or interpretation of the study results
• A positive test result for hepatitis B surface antigen, hepatitis C virus antibody, or human immunodeficiency virus types 1 or 2 antibodies at screening
• Donation of blood or blood products > 450 mL within 30 days of dosing

Double blind