Vaccination of neonates: Problem and issues

► Corticosteroids, cytokines and maternal antibodies affect neonatal immune responses. ► Non-rodent, non-umbilical cord blood models of neonatal immune function are needed. ► Cells and soluble mediators of adult and neonatal immune systems differ in quantity. ► Passive antibodies in adult animal models do not inherently suppress B cell responses. ► Vaccines must be optimized for use in neonates.