A Study to Evaluate the Immunogenicity of Quadrivalent LAIV (MEDI8662) in Adults 18 to 49 Years of Age

The purpose of this study was to show that quadrivalent live attenuated influenza vaccine (Q/LAIV-BFS; MEDI8662) was at least as immunogenic as two different forms of the commercial vaccine, FluMist, by comparing the strain-specific antibody levels in the blood.

The primary objective of this study was to determine the immunologic noninferiority of MEDI8662, a quadrivalent live attenuated influenza vaccine (Q/LAIV) (delivered intranasally using the blow-fill-seal \[BFS\] delivery system) (Q/LAIV-BFS) to two trivalent formulations of licensed FluMist (delivered intranasally using the Becton Dickinson \[BD\] Accuspray™ device) by comparing the strain-specific geometric mean titers (GMTs) post dosing.

Eligibility Criteria:
Inclusion Criteria:

* Male or female, age 18 through 49 years, inclusive (reached their 18th year birthday but not yet reached their 50th year birthday) at the time of randomization
* Females of child-bearing potential, must have used an effective method of avoiding pregnancy for 30 days prior to the first dose of investigational product, and must have agreed to continue using such precautions for 60 days after the dose of investigational product. In addition, the participant must also have had a negative urine or blood pregnancy test at screening and, if screening and Day 0 do not occur on the same day, on the day of vaccination prior to randomization.
* Healthy by medical history and physical examination OR presence of stable underlying chronic medical condition for which hospitalization had not been required in the previous year

Exclusion Criteria:

* Acute illness or evidence of significant active infection at randomization
* Fever greater than or equal to 100.4 degrees F (38°C) at randomization
* History of asthma
* Any drug therapy from 15 days prior to randomization or expected drug therapy through 30 days post dose with the exception of contraceptives; topical corticosteroids or antifungals for uncomplicated dermatitis; chronic medications (including those taken on an as-needed basis) that were well tolerated and were not initiated and/or did not have a dosage change within 90 days of randomization
* Previous medical history or evidence of an intercurrent illness that may have compromised the safety of the participant in the study
* Current or expected receipt of immunosuppressive medications (inhaled and topical corticosteroids and topical calcineurin inhibitors were permitted) within a 30-day window around the dose
* Receipt of immunoglobulin or blood products within 90 days before randomization into the study or expected receipt during study participation
* Receipt of any investigational drug therapy within 30 days prior to randomization or planned receipt of any investigational drug therapy through 30 days after dosing of investigational product (use of licensed agents for indications not listed in the package insert were permitted)
* Receipt of any nonstudy vaccine within 30 days prior to randomization or planned receipt of nonstudy vaccine through 30 days after dosing
* Receipt of any influenza vaccine (investigational or licensed) in 2009 prior to randomization or anticipated receipt prior to the collection of the post-dose immunogenicity blood sample for this study
* Any known immunosuppressive condition or immune deficiency disease including known or suspected infection with human immunodeficiency virus (HIV)
* History of allergic disease or reactions likely to be exacerbated by any component of Q/LAIV-BFS including allergy to eggs, egg proteins, gentamicin, or gelatin, or serious, life threatening, or severe reactions to previous influenza vaccinations
* History of Guillain-Barré syndrome
* Use of antiviral agents with activity against influenza virus (including amantadine, rimantadine, oseltamivir and zanamivir) within 30 days prior to receipt of investigational product or anticipated use within 30 days after receipt of investigational product
* Known or suspected mitochondrial encephalomyopathy
* Pregnant or lactating female
* Any condition that, in the opinion of the investigator, would interfere with evaluation of the investigational product or interpretation of participant safety or study results
* Participant, legal guardian, or immediate family member of participant who was an employee of the clinical study site or who was otherwise involved with the conduct of the study