Patient description: A 42-year-old healthy woman came to the clinic to have her flu shot in early October. She works in a rehab center and has no underlying disease. It's her first time getting the vaccine this year. She is married for 5 years and uses barrier methods of contraception. Her menstrual cycle is irregular. She does not smoke. She is not on any medications. She exercises regularly for 30 minutes a day at least 5 days a week. She has no history of allergies to any food or drugs. Her past surgical history is significant for tonsillectomy and she is otherwise healthy.

Clinical trial eligibility criteria: eligible ages (years): 18.0-49.0,  Influenza Subjects who meet all of the following may be included in the study: 1. Men and women 18 to 49 years of age, inclusive 2. Good general health status as determined by the Investigator 3. Adequate venous access for repeated phlebotomies 4. Screening laboratory results within institutional normal range or Grade 1 elevation if the Investigator documents clinical insignificance. Creatine kinase or bilirubin may be Grade 2 if associated with normal alanine aminotransferase (ALT) and aspartate aminotransferase (AST) and the Investigator considers the result not to be clinically significant due to vigorous exercise or Gilbert's syndrome 5. Negative drug and alcohol screen at Screening and predose on Day 1 6. For women who have not been surgically sterilized or have laboratory confirmation of postmenopausal status, negative pregnancy test 7. Willingness to practice a highly effective method of contraception that may but is not limited to, abstinence, sex only with persons of the same sex, monogamous relationship with a postmenopausal partner, monogamous relationship with vasectomized partner, vasectomy, surgical sterilization (hysterectomy, or bilateral tubal ligation, salpingectomy, or oophorectomy), licensed hormonal methods, intrauterine device (IUD), or consistent use of a barrier method (eg, condom, diaphragm) with spermicide for 28 days after the NasoVAX/placebo dose 8. Willingness to participate and comply with all aspects of the study through the entire study period, including nasopharyngeal swabs and blood and urine samples 9. Provision of written informed consent Subjects who meet any of the following will be excluded from the study: 1. Pregnant, possibly pregnant, or lactating women 2. Household contacts of pregnant women, children < 5 years of age, or immunocompromised individuals for the period up through 2 weeks postvaccination 3. Persons who care for pregnant women, children < 5 years of age, or immunocompromised individuals for the period up through 2 weeks postvaccination 4. Body mass index > 35.0 kg/m2 5. Positive results for HIV, hepatitis B virus, or hepatitis C virus at Screening 6. Asthma or other chronic lung disease that is greater than mild in severity. Specifically excluded are participants with the any of the following events in the past year Daily symptoms Daily use of short acting beta 2 agonists Use of inhaled steroids or theophylline Use of pulse systemic steroids Emergency care or hospitalization related to asthma or other chronic lung disease Systemic steroids for asthma exacerbation 7. History of diabetes mellitus (gestational diabetes is allowed if treatment was not required postpartum and serum glucose is currently in the normal range) 8. History of coronary artery disease, arrhythmia, or congestive heart failure 9. Clinically significant ECG abnormality as determined by the Investigator 10. Poorly controlled hypertension (systolic blood pressure > 150 mmHg or diastolic blood pressure > 95 mmHg) at Screening or predose on Day 1 11. History of anaphylaxis or angioedema 12. Known allergy to any of the ingredients in the vaccine formulation 13. History of chronic rhinitis, nasal septal defect, cleft palate, nasal polyps, or other nasal abnormality that might affect vaccine administration 14. Previous nasal surgery or nasal cauterization 15. Any symptoms of upper respiratory infection or temperature > 38°C within 3 days before Day 1 16. Any symptoms within 24 hours before Day 1 of upper respiratory illness of allergy flare-up that, in the opinion of the Investigator, presents as nasal congestion or rhinorrhea that could inhibit the proper administration of the IP 17. Known or suspected malignancy, excluding non-melanoma skin cancers and other early stage surgically excised malignancies that the Investigator considers to be exceedingly unlikely to recur 18. Immunocompromised individuals, including those who have used corticosteroids (including intranasal steroids), alkylating drugs, antimetabolites, radiation, immune-modulating biologics, or other immunomodulating therapies within 90 days before Day 1 or those who plan use during the study period 19. Use of statin medication within 30 days before Day 1 (see list in Section 6.8.1) 20. Receipt of intranasal medications (including over-the-counter medications) within 30 days before Day 1 21. Receipt of any investigational product (IP) within 30 days before Day 1 22. Receipt of any vaccine within 30 days before Day 1 23. Receipt of intranasal vaccine within 90 days before Day 1 24. Receipt of any influenza vaccine within 6 months before Day 1 25. Any change in medication for a chronic medical condition within 30 days before Day 1 26. Past regular use or current use of intranasal illicit drugs 27. Smoking of any type (eg, cigarettes, electronic cigarettes, marijuana) or use of any tobacco product within 30 days before Day 1 28. Any medical, psychiatric, or social condition or occupational or other responsibility that in the judgment of the Investigator would interfere with or serve as a contraindication to protocol adherence, assessment of safety (including reactogenicity), or a subject's ability to give informed consent