Influenza Challenge Study to Determine the Optimal Infection Dose and Safety of a Recombinant H3N2 (A/Texas/71/2017 (H3N2, Clade 3C3a) Influenza Strain

Inclusion Criteria

• Provide written informed consent prior to initiation of any study procedure
• Are able to understand and comply with planned study procedures and be available for all study visits
• Agree to remain an inpatient for at least 7 days after challenge AND until they have no viral shedding*, determined by qualitative Reverse Transcription - Polymerase Chain Reaction (RT-PCR) beginning on Study Day 6
• No viral shedding is defined as two negative RT-PCR tests 12 or more hours apart
• Healthy* males and non-pregnant, non-breastfeeding females aged > / = 18 and / = 7 days have passed since a serum pregnancy test).
• 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
• Not of childbearing potential - 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 Essure(R) placement with history of documented radiological confirmation test at least 90 days after the procedure).
• True abstinence is 100% of time no sexual intercourse (male's penis enters the female's vagina). (Periodic abstinence [e.g. calendar, ovulation, symptothermal, post-ovulation methods] and withdrawal are not acceptable methods of contraception).
• Acceptable forms of primary contraception include monogamous relationship with a vasectomized partner who has been vasectomized for 180 days or more prior to the subject receiving the influenza challenge virus, intrauterine devices, birth control pills, and injectable/implantable/insertable hormonal birth control products. Must use at least one acceptable primary form of contraception for at least 30 days prior to challenge and at least one acceptable primary form of contraception during the remainder of the study or approximately 57 days after confinement.

NOTE: These criteria are applicable to female subjects in a heterosexual relationship AND of child-bearing potential. These criteria do not apply to subjects in a same sex relationship.

• Non-habitual smoker* of tobacco, e-cigarettes or marijuana

*Non-habitual smokers are those who smoke no more than four cigarettes, other tobacco products, e-cigarettes (to include vaping and Juuling products) or marijuana in a week and agree not to smoke cigarettes, other tobacco products, e-cigarettes and/or marijuana products during participation in the study.

• 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.
• 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 for at least one week before admission and throughout the confinement period
• Negative drug urine toxicology result on screening (i.e., amphetamines, cocaine, and opiates) and on admission to the confinement unit (i.e., amphetamines, cocaine, and opiates)*

*Select drug use may be allowed at Investigator's discretion (e.g., prescribed amphetamines for ADHD)

• 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

*Oseltamivir, zanamivir, peramivir, baloxavir marboxil, amantadine (generic) and rimantadine (Flumadine and generic), aspirin, intranasal steroids, decongestants, antihistamines, and other non-steroidal anti-inflammatory drugs (NSAIDs)

• In good health*, and do not have clinically significant medical, psychiatric, chronic or intermittent health conditions including those listed in Exclusion Criteria

*Good health, as determined by medical history, medication use and physical examination to evaluate ongoing chronic medical or psychiatric diagnoses or condition