Factors affecting the immunogenicity and potency of tetanus toxoid: implications for the elimination of neonatal and non-neonatal tetanus as public health problems

An estimated 400,000 deaths occur annually from neonatal tetanus (NT). In 1989 WHO adopted the goal of eliminating NT as a public health problem worldwide. To achieve this, and to control non-neonatal tetanus (non-NT), WHO recommends that newborns be passively protected at birth by the antepartum administration of at least two doses of tetanus toxoid (TT) to their mothers and that all children subsequently receive at least three doses of diphtheria-tetanus-pertussis (DTP) vaccine. For this strategy to be effective, the TT used must be immunogenic. Potential factors that may affect TT immunogenicity need to be evaluated if NT is to be eliminated and if non-NT is to be controlled. Although data are conflicting, concurrent malarial infection may decrease the immune response to TT; however, malarial chemoprophylaxis may enhance the immune response. Malnutrition does not appear to affect immunogenicity; nevertheless, one study suggests that vitamin A deficiency is associated with an impaired immune response. Although it has been postulated that placental transfer of tetanus antibody is impaired in African women, a survey of the published literature suggests that this is not the case. Freezing TT has been shown to decrease its potency, but its impact on immunogenicity needs more evaluation.

PIP:

An estimated 400,000 children die annually due to neonatal tetanus (NT). In 1989, the World Health Organization (WHO) adopted the goal of eliminating NT as a public health problem worldwide. To that end, and in order to control non-neonatal tetanus (non-NT), the WHO recommends that newborn infants be passively protected at birth by the antepartum administration of at least 2 doses of tetanus toxoid (TT) to their mothers and that all children subsequently receive at least 3 doses of diphtheria-tetanus-pertussis (DTP) vaccine. However, the TT employed must be immunogenic in order for the strategy to work. Although the data are conflicting, concurrent malarial infection may decrease the immune response to TT, while malarial chemoprophylaxis may enhance immune response. Malnutrition does not appear to affect immunogenicity, although a study suggests that vitamin A deficiency is associated with an impaired immune response. A survey of the published literature suggests that there is no basis for accepting the hypothesis that placental transfer of tetanus antibody is impaired in African women. Finally, freezing TT has been shown to decrease its potency, but its effect upon immunogenicity remains to be determined.