How Healthy Adults Respond to the Nasal Flu Vaccine

This study is looking at how the immune system in the nose responds after receiving the FluMist nasal flu vaccine in healthy adults. FluMist is an FDA-approved influenza vaccine that is given as a nasal spray. Healthy volunteers aged 18 to 65 who do not have chronic medical conditions, do not smoke, and have not recently received a flu vaccine will be enrolled. Participants will have three study visits over approximately one week. At the first visit, participants will be screened, give informed consent, and receive the FluMist vaccine. Nasal swabs and a gentle saline nasal wash will be collected before vaccination and again at two and four days after vaccination. The samples collected will be used to study changes in immune cells, proteins, and viral activity in the nose using laboratory techniques such as gene expression and protein analysis. This information may help researchers better understand how flu vaccines work at the site where infection begins and may support the development of improved vaccines in the future. There is no direct medical benefit expected for participants. Participation is voluntary, and all study procedures will be performed by trained clinical staff.