The tetanus-diphtheria (Td) vaccine protects against toxins produced by the tetanus and diphtheria bacteria, not against the bacteria itself. There is also a combination vaccine that adds protection against pertussis (diphtheria-tetanus-pertussis vaccine).
Typically, the tetanus bacteria enter the body through a wound and begin to grow and produce the toxin. The toxin causes severe muscle spasms and can be fatal. Therefore, vaccination is particularly important.
Diphtheria usually causes inflammation of the throat and mucous membranes of the mouth. Also, the bacteria that cause diphtheria produce a toxin that can damage the heart, kidneys, and nervous system. Before routine vaccination became available, diphtheria was a leading cause of death in children.
For more information, see the Centers for Disease Control and Prevention's (CDC) Td (Tetanus, Diphtheria) vaccine information statement.
(See also Overview of Immunization.)
A diphtheria-tetanus-pertussis vaccine (DTaP) is typically given during childhood. This combination vaccine is given in five injections (at age 2, 4, 6, and 12 to 18 months and at age 4 to 6 years), followed by a booster (Tdap) that contains the same amount of tetanus vaccine but a smaller amount of diphtheria and pertussis vaccine. The booster is given at age 11 to 12 years. Because immunity against pertussis is decreasing, people over age 16 should receive the Tdap booster if they have not received it previously.
The tetanus-diphtheria (Td) vaccine is given as a booster every 10 years after the diphtheria-tetanus-pertussis booster is given at age 11 to 12 years. Also, people sometimes need to be vaccinated after an injury that breaks the skin.
Certain conditions may affect whether and when people are vaccinated (see also CDC: Who Should NOT Get Vaccinated With These Vaccines?). If people have a temporary illness, doctors usually wait to give the vaccine until the illness resolves.
Sometimes the injection site is sore, swollen, and red. Serious side effects are rare and include severe allergic reactions.
If Guillain-Barré syndrome developed within 6 weeks after a tetanus vaccine was given, people should talk to their doctor about whether future vaccinations are advisable.