Question
Tetanus toxoid vaccine
Answer
Tetanus toxoid (TT) vaccine is a formalin-inactivated preparation of tetanospasmin, the neurotoxin produced by Clostridium tetani — inactivation destroys the toxin’s toxicity while preserving its immunogenicity, allowing safe active immunization.
Composition and mechanism: the toxoid stimulates the host to produce antitoxin antibody, which, on subsequent exposure to C. tetani (via a contaminated wound), neutralizes the toxin before it can bind to neural tissue and cause disease — protection is entirely toxin-mediated (antitoxin-based), since the vaccine does not prevent colonization by the organism itself.
Administration/schedule: part of the routine childhood DPT schedule (primary series in infancy, with booster doses at 18 months and around 5 years); a Td/TT booster is given as part of adolescent/adult booster schedules and, importantly, to pregnant women (2 doses, or a single dose if previously immunized) to prevent both maternal and neonatal tetanus via passive transfer of maternal antitoxin across the placenta.
Post-exposure use: a booster dose of TT is given after a tetanus-prone wound in previously immunized individuals whose last dose was more than the recommended interval ago; in unimmunized/incompletely immunized individuals with a high-risk wound, Human Tetanus Immunoglobulin (HTIG) is additionally given for immediate passive protection, since active immunization alone would not provide protection in time.
Efficacy: highly effective and one of the most successful vaccines in preventing tetanus, including the historically devastating neonatal (umbilical) tetanus, which has been dramatically reduced through maternal immunization programmes.