Perspectives on the Development of Immune Memory Associated with Vaccination

The goal of vaccination is to induce long-term immune memory. Traditionally, immune memory has been thought to be mediated by memory T cells and B cells. In recent years, trained immunity mediated by the innate immune cells (e.g., NK cells, neutrophils, and monocytes/macrophages) has garnered increasing attention. Trained immunity exhibits an antigen-nonspecific immune memory that provides broader protection against heterologous infections. This article reviews the mechanisms involved in the development of trained immunity, memory T cells, and B cells with a particular focus on metabolic reprogramming and epigenetic modifications. Moreover, the effects of aging on immune memory and the factors involved in regulating the vaccine-induced immune memory in older people are discussed. By understanding immune memory and its regulatory mechanisms, we can better design vaccines and optimize vaccination strategies to induce long-lasting immune memory.