There is a recommended fifth dose to be administered to four- to six-year-olds.Td and Tdap are for older children, adolescents, and adults and can be injected into the deltoid muscle. These are boosters and are recommended every ten years. It is safe to have shorter intervals between a single dose of Tdap and a dose of the Td booster. Additional doses
Booster shots are important because lymphocyte production (antibodies) is not at a constant high rate of activity. This is because after the introduction of the vaccine when lymphocyte production is high, the production activity of white blood cells will start to decline. The decline in activity of the T-helper cells means that there must be a booster to help keep the white blood cells active.Td and Tdap are the booster shots given every ten years to maintain immunity for adults nineteen years of age to sixty-five years of age.Tdap is given as a one-time, first-time-only dose that includes the tetanus, diphtheria, and acellular pertussis vaccinations. This should not be administered to those who are under the age of eleven or over the age of sixty-five.Td is the booster shot given to people over the age of seven and includes the tetanus and diphtheria toxoids.
The first inactive tetanus toxoid was discovered and produced in 1924. A more effective adsorbed version of the vaccine, created in 1938, was proven to be successful when it was used to prevent tetanus in the military during World War II. DTP (which is the combined vaccine for diphtheria, tetanus, and pertussis) was first used in 1948, and was continued until 1991, when it was replaced with an acellular form of the pertussis vaccine due to safety concerns. Half of those who received the DTP vaccine had redness, swelling, and pain around the injection site, which convinced researchers to find a replacement vaccine. Two new vaccines were launched in 1992. These combined tetanus and diphtheria with acellular pertussis (TDaP or DTaP), which could be given to adolescents and adults (as opposed to previously when the vaccine was only given to children). References
Further reading
Liang JL, Tiwari T, Moro P, Messonnier NE, Reingold A, Sawyer M, Clark TA (April 2018). "Prevention of Pertussis, Tetanus, and Diphtheria with Vaccines in the United States: Recommendations of the Advisory Committee on Immunization Practices (ACIP)" (PDF). MMWR Recomm Rep. 67 (2): 1–44. doi:10.15585/mmwr.rr6702a1. ISSN 1057-5987. PMC 5919600. PMID 29702631. Kahn KE, Black CL, Ding H, Williams WW, Lu PJ, Fiebelkorn AP, Havers F, DAngelo DV, Ball S, Fink RV, Devlin R (September 2018). "Influenza and Tdap Vaccination Coverage Among Pregnant Women - United States, April 2018" (PDF). MMWR Morb. Mortal. Wkly. Rep. 67 (38): 1055–1059. doi:10.15585/mmwr.mm6738a3. PMC 6188122. PMID 30260946. World Health Organization (2018).