A Study to Evaluate the Safety and Immunogenicity of Two Doses of a Novel H5 Central Antigen mRNA-LNP in Healthy Adults

Eligibility Criteria

• 1. Provides written informed consent prior to the initiation of any trial procedures
• 2. Can understand and agrees to comply with all planned trial procedures and be available for all study visits
• 3. Adult volunteers, age 18-49 years, inclusive, at time of enrollment.
• 4. In good general health.\* \* Good health is defined by the absence of a medical condition described in the exclusion criteria. If the participant has another current, ongoing medical condition, the condition cannot meet any of the following criteria:
• 1. was first diagnosed within 3 months of enrollment with a clinically significant condition, in the opinion of investigator
• 2. had non-elective surgery, clinically significant medical procedure, or hospitalization within 3 months of enrollment;
• 3. received new prescription for systemic medication within 30 days of enrollment, unless the new prescription is in the same class of agent or a transition from generic to/from brand name equivalent; or
• 4. takes medication that may pose a risk to participant's safety or impede assessment of adverse events or study endpoints if they participate in the study.
• 5. Participants of childbearing potential\* must agree to use or have practiced true abstinence\*\* or use at least one acceptable primary form of contraception.\*\*\* \*These criteria apply to females who are in a heterosexual relationship who are of childbearing potential. Participants not of childbearing potential include post-menopausal females (defined as having a history of amenorrhea for at least one year) or a documented status as being surgically sterile (hysterectomy, bilateral oophorectomy, tubal ligation/salpingectomy, or permanently implanted contraceptive device placement).
• 6. Must agree to refrain from donating blood or blood products during the first 6 months of the study
• 7. Body mass index (BMI) 18 kg/m\^2 to 35 kg/m\^2, inclusive, and a weight of 130 kg or less at the time of screening
• 1. Positive pregnancy test at screening or prior to vaccine dose
• 2. Participant who is lactating
• 3. Presence of a significant psychiatric condition that, in the opinion of the site Principal Investigator (PI) or appropriate sub-investigator, precludes study participation
• 4. History of drug abuse or alcohol abuse within 6 months of enrollment that, in the opinion of the site PI or appropriate sub-investigator, precludes study participation
• 5. Has a significant acute illness (with or without fever), as determined by the site PI or appropriate sub-investigator, within 72 hours prior to dosing\* \*If the participant meets all other eligibility criteria, they may be enrolled and dosed once they meet this eligibility criterion. If the illness resolves within the 14-day screening window, they do not need to be rescreened, otherwise they will need to be rescreened
• 6. Currently enrolled in or plans to participate in another clinical trial with an investigational agent
• 7. Has a history of anaphylaxis to any drug compound, vaccine, food, or other substance, unless approved by the Investigator (or designee)\*\*
• 8. Received any live-attenuated or mRNA vaccine in the 28 days prior or any other vaccine in the 14 days prior to study vaccination
• 9. Has used any prohibited medication within 30 days prior to Day 1 or plans to use prohibited medications\*\*\* through Day 57
• 10. Abnormal blood pressure or temperature (Grade 1 or higher) at time of vaccination
• 11. Abnormal heart rate (Grade 2 or higher) at time of vaccination
• 12. Known and current human immunodeficiency virus (HIV), hepatitis B virus (HBV), or hepatitis C virus (HCV) infection, based on medical history
• 13. Extended exposure (e.g., occupational or home exposure) to cattle or poultry since March 1, 2024
• 14. Ingestion of non-pasteurized milk since March 1, 2024, or plans to drink non-pasteurized milk during participation in the trial
• 15. Prior receipt of an influenza A/H5 vaccine
• 16. History of myocarditis or pericarditis
• 17. Has any medical disease or condition\*\*\*\*\* that, in the opinion of the site PI or appropriate sub-investigator, precludes study participation\*\*\*\*\*\* \*\*\*\*\*Medical conditions include, but are not limited to, kidney disease with creatinine clearance \< 89 mL/min/1.73 cm2 (CKD-EPI method); known active liver disease; ischemic heart disease, clinically significant cardiac conduction disorder, arrythmia requiring treatment, congenital long QT syndrome, uncompensated heart failure; diabetes requiring insulin; neuropathy or myopathy; history of Guillain-Barré Syndrome; and malignancy (not including squamous cell skin cancer, basal cell skin cancer, or cervical lowgrade squamous intraepithelial lesions) \*\*\*\*\*\*Participation may be precluded due to safety concern or inability to adequately evaluate clinical trial endpoints.