This is a Phase 2, randomized, double-blind, placebo-controlled study of INNA-051 in healthy adults, administered prior to administration of an influenza challenge virus. This study will evaluate 2 active dose levels of INNA-051 and placebo.

Healthy participants will be administered 2 doses on INNA-051 intra-nasally and subsequently administered influenza virus as a challenge. Participants will be quarantined for 8 days. Study assessments will be performed during this period and they will monitored for symptoms of influenza infection.

Inclusion Criteria:

• Provide written informed consent
• 18 to 55 years (inclusive) at time of consent
• In good health with no history, or current evidence, of clinically significant medical conditions, and no clinically significant test abnormalities that will interfere with participant safety
• Agree to use highly effective contraception

Exclusion Criteria:

• History of, or currently active, symptoms or signs suggestive of URT or lower respiratory tract (LRT) infection within 4 weeks prior to the first study visit
• Any history or evidence of any other clinically significant or currently active systemic comorbidities including psychiatric disorders (includes participants with a history of depression and/or anxiety)
• Participants who have smoked ≥10 pack years at any time
• A total body weight ≤50 kg or body mass index (BMI) ≤18 kg/m2 or ≥35kg/m2.
• Pregnant or breast feeding
• Any significant abnormality altering the anatomy of the nose or nasopharynx that may interfere with the nasal assessments or viral challenge, clinically significant history of epistaxis, or any nasal or sinus surgery within 3 months of the first study visit
• vaccinations within the 4 weeks prior to the planned date of first dosing with IMP (10 days for SARS-CoV-2 vaccines, 6 months for influenza vaccine), or during the study
• Receipt of blood or blood products, or loss (including blood donations) of 470 mL or more of blood during the 3 months prior to dosing or planned in 3 months post.
• Receipt of any investigational product within 3 months (or 5 half-lives of the investigational product used in the other study, whichever is greater) prior to first dose with IMP, or 3 IMPs within prior 12 months, or prior administration with a virus from the same virus family as the challenge virus, or prior participation in another respiratory viral challenge study in the preceding 3 months
• Confirmed positive test for drugs of abuse or cotinine, history or presence of alcohol addiction, or excessive consumption of xanthine-containing substances
• A forced expiratory volume in 1 second (FEV1) <80%
• Positive HIV-1 or HIV-2 test, or positive test for hepatitis B or C