This study examines the effects of influenza vaccination on immune responses in adults who plan to receive their seasonal flu shot. The vaccines being studied include Flucelvax, VAXIGRIPTETRA, and INFLUVAC TETRA, which are all approved vaccines designed to protect against seasonal influenza virus strains. These vaccines contain inactivated or surface parts of different influenza virus strains and are given as a single injection into the muscle. The immune system is the body’s natural defense against infections, and this research focuses on understanding how vaccination affects specific immune cells called memory lymphocytes, which are white blood cells that help the body remember and fight off infections it has encountered before.
The purpose of this study is to examine how flu vaccination impacts two types of immune responses: resident memory immune cells found in the nasal lining and peripheral memory immune cells in the blood that can travel to the respiratory system, which includes the nose, throat, and lungs. Researchers want to understand whether getting a flu vaccine in the arm affects the immune defenses located directly in the nose and airways, where flu viruses typically enter the body. This information could help scientists better understand how flu vaccines work and potentially improve future vaccine strategies.
Participants in this study will receive one of the approved seasonal flu vaccines as they normally would during flu season. Before and after receiving the vaccine, researchers will collect samples from the nose and blood to measure changes in immune cell populations and markers that indicate how these cells move to different parts of the body. The study will also look at antibody levels, which are proteins that help neutralize viruses, and examine gene activity related to immune responses. The research is expected to begin enrolling participants in October 2025 and continue until April 2026.
France 
