FA16 Immunization Module’s Updates

DTaP, DT, Tdap, and Td – A Brief Overview of the Vaccines Against Diptheria, Tetanus, and Pertussis

I was curious about the distinguishing factors among the various vaccines for diphtheria, tetanus, and pertussis, and looked for further clarification.  This update is a brief overview of my findings, and though it does not focus directly on one of the given topics from the list, a few of the topics are incorporated as they pertain to these vaccines.  In an effort to keep the update as brief as possible, not all topics could obviously be discussed here.

Diptheria and tetanus are vaccinated against using toxoids.  A toxoid is a purified toxin that has been inactivated by formalin treatment.  Since the diseases are mediated by the secretion of toxins from Corynebacterium diptheriae and Clostridium tetani, respectively, the vaccines are aimed at creating antibodies against the toxins.[1]  Pertussis vaccines can be whole-cell or acellular in nature.  Whole-cell vaccines contain an inactivated Bordetella pertussis cell.  Acellular vaccines are subunit-based and consist of inactivated pertussis toxin and other antigens of B. pertussis in varying combinations.  While whole-cell pertussis vaccines are still used in many countries, they are no longer available in the United States.[2]

The movement from whole-cell to acellular pertussis vaccines in the United States rose due to adverse effects of the whole-cell vaccine.  Manufacturing of whole-cell vaccines does not eliminate the presence of the endotoxin and other components of B. pertussis that can lead to fever, irritability, and reactions at the injection site including redness, swelling, and pain.[3]

There are currently four combination vaccines available for the prevention of diphtheria and tetanus:  DTaP, DT, Tdap, and Td.  Two of the vaccines – DTaP and Tdap – provide protection against pertussis.  The strength of the vaccine components is indicated by the use of upper- and lower-case letters in the vaccine abbreviations.  Capital letters (D, T, and P) signify full-strength doses, whereas lower-case letters indicate reduced doses.  The strength of the doses corresponds with the target age-group of the vaccines (see below).  The lower-case “a” present in the abbreviations DTaP and Tdap implies the use of acellular components versus whole-cell as in the DTP vaccine, which is no longer utilized in the US.[4]

DTaP and DT vaccines are administered only to children under the age of 7.  DTaP vaccines contain high doses of diphtheria and tetanus toxoids as well as three to five B. pertussis acellular antigens.  The vaccine is administered in 5 doses at 2, 4, 6, and 15-18 months and 4-6 years of age.  DT vaccines are used in children who have experienced adverse reactions to the pertussis component of the DTaP vaccine.[5]

Tdap vaccines contain reduced amounts of the diphtheria toxoid and pertussis antigens.  The vaccine is administered in single doses between 11-18 years of age and then again after the age of 19.  In cases where a child over the age of 7 has not received a complete vaccination series against pertussis and has no prior history of adverse reactions to the pertussis vaccine, Tdap is administered following “catch-up” protocol.  It is also recommended that pregnant women receive a dose of Tdap between the 27th to 36th weeks of pregnancy to maximize infants’ passive immunity.  Td vaccines are used as a booster for tetanus and diptheria in adults and should be obtained every 10 years following Tdap administration.[6]

 

[1] Parham, Peter.  (2009).  Chapter 14: Vaccination to prevent infectious diseases (p. 440). The Immune System (3rd ed.). New York:  Garland Science

[2] CDC: The Pink Book, Ch. 16  (http://www.cdc.gov/vaccines/pubs/pinkbook/pert.html)

[3] Gabutti, Giovanni, et al. (2015).  Pertussis:  Current perspectives on epidemiology and prevention.  Human Vaccines and Immunotherapeutics, 11(1):  108-117.  (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4514233/) &  CDC: The Pink Book, Ch. 16  (http://www.cdc.gov/vaccines/pubs/pinkbook/pert.html)

[4] CDC:  Diptheria Vaccination – What Everyone Should Know (http://www.cdc.gov/vaccines/vpd-vac/diphtheria/public/index.html)  &  Parham, Peter.  (2009).  Chapter 14: Vaccination to prevent infectious diseases (p. 440). The Immune System (3rd ed.) New York:  Garland Science

[5] CDC: The Pink Book, Ch. 16  (http://www.cdc.gov/vaccines/pubs/pinkbook/pert.html) & CDC:  Diptheria Vaccination – What Everyone Should Know (http://www.cdc.gov/vaccines/vpd-vac/diphtheria/public/index.html) 

[6] CDC: The Pink Book, Ch. 16  (http://www.cdc.gov/vaccines/pubs/pinkbook/pert.html) & CDC:  Diptheria Vaccination – What Everyone Should Know (http://www.cdc.gov/vaccines/vpd-vac/diphtheria/public/index.html) 

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