H7N9 AI viruses have recently caused a large outbreak of severe respiratory disease in humans in China. A vaccine for use in the event of an H7N9 AI pandemic is an important research priority. Previous studies have shown that when subjects who received a live bird flu vaccine received a subsequent booster dose of inactivated bird flu vaccine, a vigorous antibody response was detected. The inactivated vaccine served as a way to probe the immune response to the initial live vaccine. The purpose of this study is to evaluate the safety, infectivity, and immunogenicity of a live attenuated H7N9 A/Anhui/13 ca influenza virus vaccine in healthy adults, and to administer a booster dose of an inactivated subvirion H7N9 influenza vaccine 3 months later.~This study will enroll healthy adults who are willing to remain in an isolation unit in an inpatient clinic for several days during the study. They will be randomly assigned to receive either one dose (Group 1) or two doses (Group 2) of the live attenuated H7N9 A/Anhui/13 ca influenza virus vaccine, which will be delivered by a nasal spray device. Participants in both groups will receive one booster dose of inactivated subvirion H7N9 influenza vaccine 3 months later in an outpatient setting. All participants will be admitted to the inpatient clinic and will receive one dose of the live attenuated H7N9 A/Anhui/13 ca influenza virus vaccine 2 days after entering the clinic. Participants will remain in the inpatient clinic for approximately 9 days after receiving the vaccine. While in the clinic, participants will undergo medical history reviews, blood collections, urine collections, physical examinations, nasal wash procedures, and vital sign measurements.~Participants in Group 1 will attend a study visit at Day 28 and undergo a medical history review, blood collection, and a nasal wash. Participants in Group 2 will be readmitted to the inpatient clinic 2 days prior to receiving a second dose of the live attenuated H7N9 A/Anhui/13 ca influenza virus vaccine at Day 28. They will remain in the clinic for approximately 9 days after receiving the vaccine; while in the clinic, they will take part in the same study procedures as during the first inpatient visit.~All participants will attend a study visit at Day 56 and undergo a medical history review, blood collection, and a nasal wash. At Day 98, all participants will receive one booster dose of the inactivated subvirion H7N9 influenza vaccine, as outpatients. They will attend additional study visits on Days 101, 105, 112, 126, 154, and 180, which may include medical history reviews; physical examinations; and urine, blood, and nasal secretion collections.
H7N9 avian influenza (AI) viruses have caused a recent outbreak of severe respiratory disease in humans in China. The purpose of this study is to evaluate the safety and immunogenicity of a live attenuated H7N9 A/Anhui/13 ca influenza virus vaccine in healthy adults. A single dose of inactivated subvirion H7N9 influenza vaccine will be administered 3 months later.