Immunity assessment is essential for implementation of optimal vaccination strategies. This has traditionally essentially relied on seroepidemiological studies assessing antibody prevalence in various populations. However, disappearance of serum vaccine antibodies may not mean absence of immunity, as recently shown for protection against hepatitis B or Haemophilus influenzae b (HIB). May surrogate markers of immunity other than serum antibody titres prove useful for immunity evaluation ? Peak antibody titres achieved after immunization directly reflect the number of vaccine-induced plasmocytes, which have a definite life span of a few months to years after which their disappearance is reflected by disappearance of serum antibodies. Antibody persistence can thus be predicted (modelling) by assessment of peak antibody titres achieved following primary immunization. Vaccine antigen-driven B cell differentiation also leads to induction of B cell memory cells, which may differentiate into new antibody-secreting cells (ASC) within a few days after antigen exposure, thus supporting protection against clinical disease after disappearance of serum antibodies (chronic hepatitis B, HIB). Identification of such memory B cells requires activation by antigenic exposure, whether in vitro or in vivo (booster). Quantification of ASC, kinetics and avidity of booster-triggered antibodies thus represent useful surrogate markers of immunity. Effector CD4+ and CD8+ T cells turn into memory T cells a few weeks after immunization. Their interest as surrogate markers depends on their capacity to confer a certain degree of clinical protection, which was recently recognized in certain conditions (measles, pertussis ?). However, the evaluation of T cell responses is yet technically difficult and only partly standardized, limiting their use at the population level. Similarly, assessment of mucosal immunity has yet proven of little use, for technical issues and in view of their short-term persistence. New approaches could further facilitate the use of various surrogate markers of immunity for implementation of vaccine strategies.