The Tetanus Vaccine

Dr. Parang Mehta, MD.

Tetanus is caused by a bacterium, Clostridium tetani.  It is found in soil and many other places, and often contaminates injuries and wounds, leading to serious and often fatal disease.  This organism produces spores that can survive in soil for prolonged periods, and can even survive boiling for a few minutes.  Vaccination against tetanus is thus very important.

Immunity to tetanus can be provided by tetanus immunoglobulin (passive immunity), and by the tetanus toxoid (active immunity).

Tetanus Toxoid

Tetanus toxoid is available alone (TT), and is mostly used in adolescents and adults.  For children, is is available in various combinations with diphtheria toxoid and pertussis vaccine (Triple, or DTP vaccine).  The amount of tetanus toxoid used is similar for adults and children, but the amounts of diptheria toxoid and pertussis vaccine are reduced in adult formulations.  The childhood doses of diptheria toxoid and pertussis vaccine cause unacceptable side effects in older children and adults, and reduced dose formulations are used in children over the age of 7 years.  Some combinations of tetanus toxoid are:

DTwP or DTP: is well known as the triple vaaccine, and has been in use for several decades.  It protects children against diphtheria, tetanus, and whooping cough (pertussis).  It contains the children's dose (higher than adult's) of the diphtheria and pertussis components.  The pertussis vaccine is the whole cell vaccine that has been in use for a long time.  This vaccine should not be used beyond the age of 7 years.

DTaP: is the newer version of the triple vaaccine.  The whole cell pertussis component is responsible for side effects like local pain and fever, and the acellular pertussis vaccine avoids those to a large extent.  Like DTwP, DTaP protects children against diphtheria, tetanus, and whooping cough (pertussis).  It is not better than the older vaccine in efficacy, but has less side effects.  

Tdap: has a lower dose of diptheria toxoid and the acellular pertussis vaccine components, and is suitable for use in adolescents and children.

dT contains a normal amount of tetanus toxoid, but a reduced amount of the diphtheria toxoid.  This is suitable for the ten or 15 year booster of tetanus.  It is a recent introduction, to combat the incidence of diphtheria in adolescents.

DT: a combination of child strength ditheria and tetanus toxoids, for use in those children in whom pertussis vaccine cannot be given.  This vaccine should not be used beyond the age of 7 years.

Hexavalent vaccines: combine DTaP with hepatitis B, hemophilus influenzae type b, and injectable polio vaccines, to reduce the number of injections babies need to take.  

Vaccination Schedule

Children should receive 3 doses of DTwP or DTaP in the first year.  This can be started at 6 weeks, and the minimum interval between doses is 4 weeks.  6-8 weeks is preferred, though, as the protective levels are better.  This should be followed by a booster dose of DTwP or DTaP in the second year, usually at the age of 18 months.  Another booster is required at the age of 4-5 years.

Antibody titres fall gradually, and boosters are required every 8-10 years.  A booster of dT or Tdap should be given at the age of 10-12 years.  If tetanus toxoid is given as part of wound management at any time, no more doses should be given for ten years.

Last Revision: February 11, 2016

The Toxin and the Toxoid

Tetanus is caused by the neurotoxin, tetanospasmin, also called tetanus toxin.  This is a very poisonous substance - the lethal dose is estimated to be one millionth of a milligram per kilogram of body weight.  Among the known poisons, only the botulinum toxin is more poisonous.  

The tetanus toxin is stored inside the bacteria, and is released on death of the bacteria.  It attaches to the distal nerve endings near the injury site, and travels up the nerve to the spinal cord.  

Tetanus immune globulin binds to this toxin and neutralizes it in the blood and tissues before it binds to the nerves.  Once tetanospasmin binds to the nerves, nothing can be done.  

The toxoid is a preparation of the toxin that has been modified by heating or chemical treatment.  This toxoid cannot cause disease, but stimulates the immune system of the recipient to produce antibodies against tetanospasmin.  

A person who has received the tetanus vaccination can get Clostridium tetani infection.  However, the toxin produced will be neutralized by the antibodies, and the person will not suffer tetanus.  The tetanus vaccine is almost 100% effective in persons who have taken a full series.

Contact Information

Dr. Parang Mehta,
Mehta Childcare,
Opposite Putli, Sagrampura,
Surat, India.    Tel: +91 9429486624.