Single Dose Texas 2017 (H3N2) Challenge Study

Inclusion Criteria: 1. Provide written informed consent prior to initiation of any study procedure 2. Are able to understand and comply with planned study procedures and be available for all study visits 3. Agree to remain an inpatient for at least 7 days after challenge AND until they have no viral shedding, determined by qualitative RT-PCR beginning on Study Day 6 4. Healthy males and non-pregnant, non-breastfeeding females aged ≥ 18 and \< 46 years of age at enrollment NOTE: Female subjects of childbearing potential must have a negative serum pregnancy test at screening, a negative urine pregnancy test upon admission to the confinement unit AND a negative pregnancy test before any CXR (if ≥ 7 days have passed since a serum pregnancy test). 5. Women of childbearing potential must agree to use or have practiced true abstinence or use at least one acceptable primary form of contraception for at least 30 days prior to challenge 6. Non-habitual smoker of tobacco, e-cigarettes or marijuana 7. No self-reported or known history of alcoholism within the last 2 years and agrees to abstain from alcohol for at least one week before admission and throughout the confinement period 8. No self-reported or known history of restricted drug use for at least 30 days prior to challenge and agrees to abstain from restricted drugs throughout the confinement period 9. Negative drug urine toxicology result on screening (i.e., amphetamines, cocaine, and opiates) and on admission to the challenge unit (i.e., amphetamines, cocaine, and opiates) 10. Agree not to use the listed prescription or over the counter medications within 7 days prior to and through confinement period, unless approved by the investigator 11. In good health, and do not have clinically significant medical, psychiatric, chronic or intermittent health conditions including those listed in Exclusion Criteria 12. Vital signs as follows: * Pulse is 47 to 99 beats per minute, inclusive * Systolic blood pressure is 85 to 139 mmHg, inclusive * Diastolic blood pressure is 55 to 89 mmHg, inclusive * SpO2 \> 95%; RR \< 18 * Oral temperature is less than 100.6°F 13. Eligibility laboratory values (WBC, Absolute Lymphocyte Count, Hgb, PLTs, ALT and Cr) are within acceptable parameters 14. Body mass index (BMI) \>18.5 and \<40 kg/m2 at screening 15. Other screening tests (ECG and CXR) are within normal reference range or not deemed clinically significant by the PI or appropriate sub-investigator 16. Negative test for HIV, hepatitis B virus (HBV), and hepatitis C virus (HCV) at screening 17. Negative multiplex respiratory virus panel on Day -2, and Day -1 18. Negative RT-PCR test for SARS-CoV-2 on screening and Day -2 19. HAI antibody titer ≤1:40 against influenza A/Texas/71/2017 (H3N2) at screening Exclusion Criteria: 1. Presence of self-reported or medically documented significant medical or psychiatric condition(s) NOTE: Significant medical or psychiatric conditions include but are not limited to: 1. Respiratory disease (e.g., chronic obstructive pulmonary disease \[COPD\], asthma) requiring daily medications \[Inhaled, oral or intravenous (IV) corticosteroids, leukotriene modifiers, long and short acting beta agonists, theophylline, ipratropium, biologics\] or any treatment for respiratory disease exacerbations (e.g., asthma exacerbation) within the last 5 years 2. Presence of any febrile illness or symptoms suggestive of a respiratory infection within two weeks prior to challenge 3. Significant cardiovascular disease (e.g., congestive heart failure, cardiomyopathy, ischemic heart disease) or history of myocarditis or pericarditis as an adult. 4. Neurological or neurodevelopmental conditions (e.g., epilepsy, stroke, seizures, encephalopathy, focal neurologic deficits, Guillain-Barre syndrome, encephalomyelitis or transverse myelitis). 5. Ongoing malignancy or recent diagnosis of malignancy in the last five years (excluding basal cell carcinoma of the skin) 6. Presence of an autoimmune disease. 7. Immunodeficiency of any cause. 8. History of diabetes. 2. Presence of immunosuppression or any medications that may be associated with impaired immune responsiveness 3. Known allergy or intolerance to treatments for influenza (including any neuraminidase inhibitors or baloxavir marboxil). 4. Known allergy to two or more classes of antibiotics (e.g., penicillins, cephalosporins, fluoroquinolones, or glycopeptides). 5. Known allergy to excipients in the challenge virus inoculum. 6. Receipt or planned receipt of any investigational drug/investigational vaccine/licensed vaccine, except for a licensed or emergency use authorized COVID-19 vaccine product, within 30 days prior to the date of challenge. 7. Prior enrollment in an influenza virus challenge study with an influenza virus of the same subtype within the past 2 years. 8. Currently enrolled in any investigational study or intends to enroll in such a study within the ensuing study period. 9. Receipt of any influenza vaccine four months prior to challenge or plans to receive influenza vaccine during the study (approximately 28 days after challenge). 10. History of a previous severe allergic reaction to any drug or biologic with generalized urticaria, angioedema, or anaphylaxis. 11. Receipt of blood or blood products during the six months prior to the planned date of challenge. 12. Plans to donate blood or blood products during the study (approximately 80 days). 13. Any condition (including medical and psychiatric conditions) that, in the opinion of the Investigator, might interfere with the safety of the subject and/or study objectives. 14. An ongoing symptomatic condition for which subject has had or has ongoing medical investigations but has not yet received a diagnosis or treatment plan e.g., ongoing fatigue without a diagnosis. 15. Known close contact with anyone known to have or suspected to have a respiratory viral illness within 7 days prior to challenge. 16. Significant abnormality altering anatomy of nose/nasopharynx (including significant nasal polyps), clinically significant nasal deviation, or nasal/sinus surgery within 180 days prior to challenge. 17. History in the last five years of chronic or frequent intermittent sinusitis. 18. Recent history (180 days) of epistaxis or anatomic or neurologic abnormality impairing the gag reflex or contributing to aspiration. 19. Currently using an internal cardiac device such as a pacemaker or other implanted electronic medical devices.