Tetanus is a neurotoxin produced by a gram -ve bacterium called clostridium tetani. They enter the body through unclean wounds. In the body, they produce a neurotoxin. They enter the peripheral nerves, and also the spinal cord.
They affect the spinal inhibitory interneurons. Neurons such as corticospinal neurons are released from inhibition, causing uncontrollable contractions called tetanic spasms.
Both TT and ATS are available for intramuscular or subcutaneous application. ATS, a solution of purified and pre-formed antibodies, is used to prevent and cure tetanus. It is gotten from purified equine blood. The method of preparation is through horses hyperimmunized with tetanus toxin. It is used mostly for patients who have not been immunized with the toxoid and are therefore more prone to tetanus attacks.
Tetanus toxoid is an antigen. It is formed from a tetanus toxin detoxified with formaldehyde. It is then purified through fractionation with ammonium sulfate and adsorbed to aluminum phosphate. It induces a strong T cell-specific immune response against Clostridium tetani neurotoxin after receiving the vaccine.
Both can be given to a patient in some circumstances. In such cases, separate syringes and sites of injection should be used to avoid neutralizing the toxoid. It is also important that epinephrine is always available while given TT or ATS in case there is a hypersensitivity reaction, like anaphylaxis.
Differences between the two tetanus vaccines (ATS and TT)
|Anti Tetanus Serum (ATS)||Tetanus Toxoid (TT)|
|ATS is an anti-tetanus serum that can
be used for both prevention and
treatment of tetanus.
|TT is a tetanus toxoid used for both pre and post-exposure prophylaxis in tetanus. It is only used for prevention.|
|It is obtained from hyperimmunized
|It is gotten from an inactivated Clostridium tetani toxin.|
|It has a faster onset of action than TT||Has low onset of action as it goes into the blood and stimulates immunity. The body immunity will produce antibodies against Clostridium tetani|
|250 units are given, it is increased to 500 units in cases of wounds older than 24 hours||0.5 ml is given at different intervals|
|Passive immunity against tetanus in a tetanus-prone wound.||Active immunization against tetanus, neonatal tetanus, and tetanus-prone wound management|
|Given only intramuscularly||Given intramuscularly|
TT is given in 5 doses for primary immunization (0.5 ml given, not less than 4 weeks between the first and second, 6 months between the second and third. A further dose is given a year after the primary doses and then the fifth dose, a year later.
A booster dose is then given after every 10 years unless there is an injury (after two years of having a booster dose).