Influenza virus causes seasonal flu epidemics which kill up to 600,000 people globally each year. The current flu vaccine induces our immune response to produce antibodies which bind to structures present on the outside of the virus rendering them unable to infect our cells. Unfortunately, this complex virus constantly changes these structures at an extremely fast rate, meaning that our existing antibodies struggle to recognise and respond to altered or completely new versions which appear each year. As a result, unlike vaccines for other infectious diseases, the flu vaccine has to be reformulated each year, leading to annual variation in how well it works. It also doesn’t protect against every flu strain which is how pandemics, such as the 2009 “swine flu” outbreak, occur. The flu vaccine needs to be improved so that it can offer more widespread protection that lasts for life. Researchers are trying to improve this by instead pushing the vaccine to induce a different arm of the immune response called T cells. These recognise components buried deep within the virus which don’t change, meaning they can provide long-lasting protection and respond to different strains. My research focuses on the basic science at the heart of this. I explored whether another immune cell, macrophages, provide important signals to T cells after the first infection with influenza by blocking interactions between the two. It is thought that these signals promote the formation of the long-term T cell population which provides protection from influenza if reinfection occurs.