Influenza A viruses are widely found in nature and can infect a wide variety of birds and mammals, including humans. Some types of influenza A viruses are more likely to spread from animals to humans, and researchers are interested in monitoring these viruses and developing potential vaccines for them. H7N7 is one type of influenza A virus. In recent years, there have been several H7N7 outbreaks among humans, and the development of an H7N7 vaccine is a high priority. This study will enroll two groups of participants: people who have previously received one of three types of a pandemic LAIV as part of a research study and people who have not previously received a LAIV vaccine. The purpose of this study is to evaluate the safety and immunogenicity of a single dose of an inactivated H7N7 vaccine in these two groups of participants.~At a baseline study visit, all participants will undergo a medical history review, physical examination, vital sign measurements, blood collection, and nasal secretion collection. Female participants will provide a urine sample for pregnancy testing. All participants will then receive one intramuscular (IM) injection of the H7N7 study vaccine in their upper arm. They will remain in the clinic for 30 minutes for observation and monitoring. Participants will monitor and record any adverse symptoms between study visits. Additional study visits will occur at Days 4, 7, 14, 28, 56, and 180. At select study visits, participants will undergo a medical history review, physical examination, and nasal secretion collection. Blood collection will occur at each visit; some blood samples may be stored for future research.
H7N7 is one type of influenza virus that may pose a threat to humans if an outbreak occurs. This study will evaluate the safety and immune response to an H7N7 vaccine in people who have previously received a live attenuated influenza vaccine (LAIV) as part of a research study and people who have not previously received a LAIV.