Interdisciplinary work between psychologists and immunologists has shown that factors like stress could be the trigger that leads to the development of a bout of illness. By studying the response to vaccination, we can examine immune function in the context of the rest of the body in a clinically meaningful way. This technique has been used to demonstrate consistent relationships between stress and the response to influenza vaccination and other vaccines, as well as links between other factors, such as social support and personality, and vaccination-induced protection against disease. There are several ways the vaccination response can be used to understand more about how stress influences immunity. In addition, specific types of stress and other factors that influence our immune response appear to differ across different populations, which emphasises the importance of taking a life course approach to studying these relationships.