FACTORS AFFECTING THE IMMUNOGENICITY AND POTENCY OF TETANUS TOXOID - IMPLICATIONS FOR THE ELIMINATION OF NEONATAL AND NONNEONATAL 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 pro blem 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 toro id (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. Potent ial 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 dat a are conflicting, concurrent malarial infection may decrease the immu ne 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 associ ated with an impaired immune response. Although it has been postulated that placental transfer of tetanus antibody is impaired in African wo men, a survey of the published literature suggests that this is not th e case. Freezing TT has been shown to decrease its potency, but its im pact on immunogenicity needs more evaluation.