Age is an important determinant in humoral and T cell responses to immunization with hepatitis B surface antigen.

The aging of the immune system, also named immunosenescence, affects vaccine responses. However, the onset of age-related immunosenescence has been uncertain, in particularly with regard to vaccine responses. Here, we show that the formation of antibodies in response to vaccination against hepatitis B virus infection was significantly reduced for donors with a mean age of 61 y compared with a group with a mean age of 33 y.