Just to add to Dr. Yakubu's thorough response above:
In the case of an injury, if the injury is severe or the patient’s previous tetanus immunization history is unknown, physicians may still give a dose of TTCV (preferably Td). In these cases where a person's vaccination status is incomplete or unreliable, it is recommended that they return to complete the full schedule (as described above), to ensure lifelong protection.
WHO proposes 6 doses of tetanus toxoid containing vaccines (TTCV) when started from infancy. These include the 3 DTP/Penta doses given at 6, 10 and 14 weeks by most countries, then the first booster dose at the second year of life, second booster dose from 4-7 years of age and the third booster dose from 9-15 years of age.
For those first exposed to the vaccine as adolescents or adults with no reliable record of being vaccinated early in life, the WHO recommendation is for 5 doses - first dose at first contact, second dose at-least 4 weeks later, third dose at-least 6 months after the second dose, fourth dose at-least 1 year after the third dose, and fifth dose at-least 1 year after the fourth dose.
Ideally the dosage of tetanus vaccine that may be required after an injury will depend on the person's immunization status. A person who has received the required doses (fully vaccinated) dose not need to be vaccinated. With the understanding that one dose of TTCV only primes the system and immunity is only conferred after the second and subsequent doses, you can see that even for the person who is not fully vaccinated giving a dose at the time of injury is only going to be useful against the next injury as it takes around 12 days for the vaccine to confer immunity after the last dose in a primed person (who has taken only one dose) or in the person who was previously protected but has lost the protected due to too long interval between the doses.
Thanks Dr. Dhrupthob for the post. These questions have puzzled us for quite long. We have not been able to find appropriate answers so far. Appreciate, if experts could throw light to address this confusion.
First, I think every country has a different immunization schedule. In my country Somaliland, we have five TT vaccine doses planned in the immunization schedule: first and second doses within the first month of life, the third dose is given after 6 month, the fourth dose is given after one year and the fifth and last dose is given after one year.
Regarding booster injections after injury (>=7 years): - If primary immunization confirmed and the wound is clean and minor: no need for injection. - If unknown or uncertain prior immunization (or less than 3 doses) in clean, minor wound: 0.5 mL IM. - All other dirty wounds (contaminated with feces, soil, and saliva): 0.5 mL IM along with tetanus immune globulin. The next booster dose not needed for 10 years thereafter.