This is an observer-blinded, randomized, placebo-controlled, parallel group study to evaluate safety and immunogenicity of TAP-V001 quadrivalent influenza vaccine in healthy adult subjects.

Subjects will be screened up to 14 days (Day -14 to Day 0) before randomization.

On the planned day of vaccination (Day 1), subjects will be randomized in a 1:1:1:1 ratio (N = 30 subjects/group) to receive study vaccine or placebo by intramuscular (IM) injection.

Approximately 5 subjects per group (N = 20) will be enrolled in parallel initially, and safety data through Day 8 will be collected. An Independent Data Monitoring Committee (IDMC) will convene to review Day 8 safety data before any additional subjects will be enrolled. If there are no safety concerns in the IDMC meeting, study enrollment will continue.

Blood and serum samples for safety laboratory tests and HAI titers will be obtained at baseline on Day 1 before administration of vaccine dose and after vaccination.

Inclusion Criteria

1. Have read, understood, and signed the informed consent form (ICF)
2. Healthy adult males and females ages 18 to 49 years, inclusive at screening
3. Body mass index (BMI) of ≥18 and ≤34 kg/m2 at screening
4. Must be in general good health before study participation with no clinically relevant abnormalities that could interfere with study assessments
5. Women of childbearing potential (WOCBP) and men whose sexual partners are WOCBP must be able and willing to use at least 1 highly effective method of contraception during the study and for 3 months after the study completion. A female subject is considered to be a WOCBP after menarche and until she is in a postmenopausal state for 12 consecutive months (without an alternative medical cause) or otherwise permanently sterile (for which acceptable methods include hysterectomy, bilateral salpingectomy, and bilateral oophorectomy).
6. Female subjects of childbearing potential must have a negative urine pregnancy test before vaccination
7. Must be able to attend all visits for the duration of the study and comply with all study procedures, including completion of Diary Card according to the study schedule.

Exclusion Criteria

1. History of an acute or chronic medical condition that, in the opinion of the investigator, would render vaccination unsafe or would interfere with the evaluation of responses.

2. History of ongoing clinical condition or medication or treatments that may adversely affect the immune system.

3. Individuals with any elevated (Grade 2 or higher) laboratory test assessed as clinically significant by investigator at screening

4. Individuals with any elevated (Grade 2 or higher) liver function enzyme at screening, regardless of the appraisal of clinical significance (cannot be retested to qualify for study). See below the criteria for excluding subjects with elevated liver enzymes:

   • Alanine aminotransferase (ALT)/aspartate aminotransferase (AST): >3 × upper limit of normal (ULN)
   • Total bilirubin: >2 × ULN
   • Alkaline phosphatase (ALP)/gamma-glutamyl transferase (GGT): >2.5 × ULN

5. Active neoplastic disease (excluding nonmelanoma skin cancer that was successfully treated) or a history of any hematological malignancy. For this criterion, "active" is defined as having received treatment within the past 5 years.

6. Long-term (greater than 2 weeks) use of oral or parenteral steroids or high-dose inhaled steroids (>800 μg/day of beclomethasone dipropionate or equivalent) within 6 months before screening (nasal and topical steroids are allowed)

7. History of autoimmune or inflammatory disease

8. Women currently pregnant, nursing, or planning a pregnancy between enrollment and 181 days after randomization

9. History of a previous serious adverse reaction to any influenza vaccine

10. History of Guillain-Barré Syndrome

11. History of anaphylactic-type reaction to injected vaccines

12. Known or suspected hypersensitivity to 1 or more of the components of TAP-V001

13. History of illicit drug use or alcohol abuse in the year before screening

14. Receipt of any influenza vaccine within 6 months before screening

15. Receipt of any vaccine within 1 month before screening

16. Acute illness or fever within 3 days before study enrollment (enrollment may be delayed for full recovery if acceptable to the investigator)

17. Individuals currently participating or planning to participate in a study that involves an experimental agent (vaccine, drug, biologic, device, or medication); or who have received an experimental agent within 1 month before enrollment in this study; or who expect to receive another experimental agent during participation in this study; or who intend to donate blood during the study period.

18. Receipt of immunoglobulin or another blood product within the 3 months before enrollment in this study or those who expect to receive immunoglobulin or another blood product during this study.

19. Individuals who plan to receive another vaccine, including seasonal influenza vaccine, during the entire 6-month study period.

Plan is to share study data by dosing group in publications