Diphtheria Tetanus Pertussis (DTaP) Vaccine

Mechanism of Action

The DTaP vaccine is a combination of diphtheria, tetanus, and pertussis. It comprises diphtheria, tetanus toxoids (inactivated toxins), and acellular pertussis antigens. The tetanus component of the vaccine is about 5 to 10 levels of flocculation units of manufactured tetanus toxoid. The diphtheria component is a manufactured diphtheria toxoid of about 15 to 25 levels of flocculation units. The acellular pertussis component of a DTaP vaccine consists of manufactured pertussis antigens called pertussis toxin, filamentous haemagglutinin, pertactin, and fimbriae type 2 and 3.[1] The vaccine produces an active immune response in the body by developing antibodies and antitoxins against the toxoids and acellular pertussis antigens. Two single DTaP vaccines are available in the United States and approved by the FDA.

Administration

The CDC’s Advisory Committee on Immunization Practices (ACIP) recommends administering the DTaP 5-dose vaccine series for children 6 weeks continuing through to 6 years of age.[5] Routine dose recommendations are for the following ages:

• Two months: minimum age of 6 weeks
• Four months: the second dose should be given at least 4 weeks after the first
• Six months: the third dose should be given at least 4 weeks after the second
• Fifteen through eighteen months: The minimum age for the fourth dose is 12 months, and it should be given at least 6 months after the third dose. It may be counted as valid if given at least 4 months after the third dose and the child was at least 12 months old.
• Four through 6 years: the minimum age for the fifth dose is 4 years old. The dose should be given at least 6 months after the fourth dose. 

The DTaP dose is 0.5 mL and given intramuscularly. The preferred intramuscular injection site for infants to 2 years of age is the anterolateral aspect of the thigh. For children 3 years of age and older, the preferred site is the deltoid muscle.[1] DTaP vaccines can also be available in combination with other childhood vaccines. Children unimmunized or incompletely immunized should receive catch-up immunizations. This process is possible with minimal intervals between doses. 

• Dose 1 to dose 2 - 4 weeks
• Dose 2 to dose 3 - 4 weeks
• Dose 3 to dose 4 - 6 months; the minimum age for dose 4 is 12 months.
• Dose 4 to dose 5 - 6 months

DTaP is approved during the last 3 months of pregnancy to prevent pertussis in infants under 2 months old.

Adverse Effects

Whole-cell pertussis vaccines, or DTP vaccines, were commonly associated with local adverse events, including swelling, redness, and pain at the injection site. DTaP vaccines replaced DTP vaccines in the 1990s to reduce the number of these common adverse events. Less common adverse events for pertussis vaccines are seizures, hypotonic-hyporesponsive episodes, and prolonged crying.[1][4] Vaccines with tetanus toxoids can cause brachial neuritis based on case reports and studies reviewed by the World Health Organization and ACIP. The cases can be severe but are rare, and brachial neuritis is usually self-limited.[1][2] ACIP has reviewed several studies regarding the simultaneous administration of DTaP with other vaccines. There may be an increased risk of febrile seizures within 24 hours when administering the inactivated influenza vaccine and the pneumococcal 13-valent conjugate vaccine or the DTaP vaccine. The overall risk for febrile seizures is small with any combination of vaccines. Therefore, the ACIP recommends a simultaneous administration of these vaccines.[1]

Contraindications

Severe allergic reactions or anaphylaxis after administration of the DTaP vaccine or vaccine component is considered a contraindication. Encephalopathy (coma, a decreased level of consciousness, or prolonged seizures) that occurs within 7 days of DTaP administration and with no identifiable cause is also a contraindication. Pregnancy should not be considered a contraindication to DTaP vaccination.[6][7][8]

Monitoring

ACIP reviewed studies that showed children developed a significant antibody response and antitoxin levels of the diseases after 3 to 4 doses of either Infanrix or Daptacel. The Vaccine Adverse Event Reporting System and Vaccine Safety Datalink surveyed any adverse events with the acellular pertussis vaccine in the United States. Overall, the studies support the safety of DTaP.[1] Clinicians should defer vaccines with pertussis components in infants or children with suspected or evolving neurological disease, including seizures. Vaccination with pertussis components can begin or resume upon establishing a treatment regimen, or the condition has stabilized.[1] An Arthus reaction (type III hypersensitivity reaction) can occur after administering vaccines with diphtheria toxoids or tetanus toxoids.[9] Symptoms of the reaction include severe pain, swelling, induration, edema, hemorrhage, and occasionally necrosis. The reaction is rare after vaccine administration and resolves over time. An Arthus reaction is not a contraindication to the DTaP vaccine, but any vaccines with tetanus toxoids should be administered every 10 years.[1]

Toxicity

There is no known antidote or treatment for the DTaP vaccine. Anaphylaxis can occur but is extremely rare. The reaction is treatable with an intramuscular injection of epinephrine.[10]

Enhancing Healthcare Team Outcomes

Vaccine coverage is considered high among infants, children, and adolescents, but clinical data shows that adults have reduced immunity. Vaccine coverage declines with increasing age, resulting from waning immunity or non-vaccination. Vaccines with acellular pertussis do not protect for as long as the prior whole-cell pertussis vaccines. In 2005, the ACIP recommended that adolescents and adults over 10 receive a single dose of tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (TdaP) vaccine. After receiving Tdap, adolescents and adults recommend receiving a booster dose of tetanus and diphtheria toxoids (Td) vaccine every 10 years or when indicated for wound management.

In 2012, ACIP recommended a dose of Tdap for women during each pregnancy to reduce the burden of pertussis in infants. Clinical studies indicated that newborn infants of mothers vaccinated during pregnancy had higher concentrations of pertussis antibodies at birth compared to newborns of unvaccinated mothers during pregnancy. In various healthcare settings, exposure to pertussis can occur to healthcare providers, patients, or hospital visitors. Depending on the approach, managing exposure or pertussis outbreak can be complicated and costly. Postexposure prophylaxis is recommended for healthcare personnel in contact with persons at risk for pertussis. This prophylaxis includes antibiotic treatment with a macrolide such as azithromycin and immediate evaluation of persons with an illness that presents with a cough.

Vaccination programs, in general, require an interprofessional team approach. The treating physician (MD, DO, NP, or PA) orders these, often administered by nursing staff. Pharmacists assist in dose preparation and must know the vaccination schedules or have access to them; many states permit pharmacists to administer vaccines subject to age limitations. This scope of practice for pharmacists continues to expand, depending on the state.[11] To be sure, all healthcare team members should familiarize themselves thoroughly with the various vaccination schedules. Nursing is in the best position to monitor for adverse events or allergic reactions, which, while rare, can occur. These events should be reported to the physician immediately. Only through this type of collaborative interprofessional care can tetanus/diphtheria/pertussis vaccines be administered most effectively for optimal results.