T Cell Immunity against Influenza: The Long Way from Animal Models Towards a Real-Life Universal Flu Vaccine

Current flu vaccines rely on the induction of strain-specific neutralizing antibodies, which leaves the population vulnerable to drifted seasonal or newly emerged pandemic strains. Therefore, universal flu vaccine approaches that induce broad immunity against conserved parts of influenza have top priority in research. Cross-reactive T cell responses, especially tissue-resident memory T cells in the respiratory tract, provide efficient heterologous immunity, and must therefore be a key component of universal flu vaccines. Here, we review recent findings about T cell-based flu immunity, with an emphasis on tissue-resident memory T cells in the respiratory tract of humans and different animal models. Furthermore, we provide an update on preclinical and clinical studies evaluating T cell-evoking flu vaccines, and discuss the implementation of T cell immunity in real-life vaccine policies.

Automated summary

Current flu vaccines mainly rely on strain-specific antibodies which may not protect against drifted or newly emerged strains. Therefore, research on universal flu vaccines that target conserved parts of the virus is a top priority. Tissue-resident memory T cells in the respiratory tract play a crucial role in providing efficient heterologous immunity, making them key components of universal flu vaccines. Recent studies on T cell-based flu immunity, along with preclinical and clinical trials of T cell-evoking vaccines, are crucial for the development of effective flu vaccine policies.