Haemophilus Type B Conjugate Vaccine + Tetanus Toxoid

Usage

• This vaccine is prescribed for the prevention of invasive diseases caused by Haemophilus influenzae type b (Hib), a bacterium that can lead to serious illnesses like meningitis, pneumonia, and epiglottitis, primarily in infants and young children. It is part of routine childhood immunizations in many countries.
• Pharmacological classification: Vaccine (bacterial polysaccharide conjugate vaccine).
• Mechanism of action: This is a conjugate vaccine where the Hib capsular polysaccharide is conjugated to tetanus toxoid. This conjugation allows the immune system of infants (whose immune systems are still developing) to recognize and mount a stronger immune response to the polysaccharide, producing antibodies against Hib. The tetanus toxoid acts as a carrier protein to enhance the immune response.

Alternate Names

• Hib conjugate vaccine (PRP-T), where PRP stands for polyribosylribitol phosphate, the Hib capsular polysaccharide, and T for tetanus toxoid.
• Brand names: ActHIB, Hiberix.

How It Works

• Pharmacodynamics: The vaccine stimulates the immune system to generate antibodies against Hib. These antibodies opsonize (mark) Hib bacteria for destruction by phagocytic cells and prevent their spread in the body. Protection against invasive Hib disease is generally achieved within a few weeks after the primary vaccination series is completed. The tetanus toxoid component induces an immune response against tetanus toxin.
• Pharmacokinetics: The vaccine is administered intramuscularly. The conjugated polysaccharide is processed by antigen-presenting cells, which leads to the activation of T-helper cells and subsequently B cells that produce specific anti-Hib antibodies. The vaccine components are eventually metabolized and cleared from the body, similar to other protein-polysaccharide conjugates. Elimination pathways would likely be similar to other polysaccharide vaccines, mainly through phagocytosis and breakdown in the reticuloendothelial system.
• Mode of action: The vaccine mimics a natural Hib infection without causing disease. The PRP-T conjugate is recognized as a foreign antigen, initiating an immune response involving T cells and B cells. Specific antibodies are produced that are directed against Hib, conferring immunity.
• There is no direct receptor binding, enzyme inhibition, or neurotransmitter modulation associated with the vaccine’s action. Its effects are mediated by immune system activation.

Dosage

Standard Dosage

Infants (primary series):

ActHIB, Hiberix, Pentacel, Vaxelis: 0.5 mL intramuscularly at 2, 4, and 6 months of age. PedvaxHIB: 0.5 mL intramuscularly at 2 and 4 months of age.

Infants (booster dose):

0.5 mL intramuscularly at 12-15 months of age (any Hib vaccine can be used for the booster except for Vaxelis)

Adults:

Not routinely recommended for healthy adults. Specific recommendations exist for adults with certain medical conditions (asplenia, complement deficiency, post-HSCT).

Clinical Use Cases

The listed clinical scenarios (Intubation, Surgical Procedures, Mechanical Ventilation, Intensive Care Unit (ICU) Use, Emergency Situations) are not typical use cases for Hib or tetanus vaccines. These vaccines are primarily used as preventive measures against infections rather than treatments during acute medical situations.

Dosage Adjustments

• Renal/Hepatic Impairment: No specific dosage adjustments are typically needed for Hib vaccine.
• Other conditions: Dosage adjustments are not generally required for metabolic disorders or genetic polymorphisms. However, consultation with a specialist may be advisable.

Side Effects

Common Side Effects

• Injection site reactions (pain, redness, swelling).
• Fever.
• Irritability, fussiness, drowsiness.

Rare but Serious Side Effects

• Allergic reactions (e.g., anaphylaxis).
• Seizures (febrile).

Long-Term Effects

No known long-term side effects associated specifically with the Hib vaccine.

Adverse Drug Reactions (ADR)

Any severe allergic reaction, including anaphylaxis, constitutes a serious ADR and requires immediate medical attention.

Contraindications

• History of severe allergic reaction to any component of the vaccine, including tetanus toxoid or any previous dose of Hib-containing vaccine.

Drug Interactions

• Immunosuppressive drugs: May reduce the effectiveness of the vaccine.
• Other Vaccines: Can generally be co-administered with other routine childhood vaccines, but preferably at different injection sites using separate needles and syringes. Mixing different vaccines in the same syringe is generally not recommended unless specifically approved for certain combination vaccines.

Pregnancy and Breastfeeding

• Pregnancy: No known adverse effects on fetal development, although limited clinical trials have been conducted specifically in pregnant women. Vaccination may be considered during pregnancy if the risk of Hib infection is high.
• Breastfeeding: Safe to administer to breastfeeding women, and antibodies may be passed to the infant through breast milk, providing additional passive protection.

Drug Profile Summary

• Mechanism of Action: Induces an immune response against Hib and tetanus toxoid.
• Side Effects: Primarily local reactions at the injection site, fever, irritability. Rarely, allergic reactions or febrile seizures.
• Contraindications: Severe allergy to any vaccine component.
• Drug Interactions: Immunosuppressants may reduce efficacy; avoid mixing with other vaccines in the same syringe unless explicitly permitted for specific combination vaccines.
• Pregnancy & Breastfeeding: Generally safe.
• Dosage: See detailed section above.
• Monitoring Parameters: Monitor for any signs of allergic reactions or other adverse events following vaccination.

Popular Combinations

This vaccine is often given as part of combination vaccines that also protect against diphtheria, tetanus, pertussis, polio, and/or hepatitis B (e.g., Pentacel, Infanrix hexa, Vaxelis).

Precautions

• Do not administer intravenously, intradermally, or subcutaneously. Intramuscular administration is essential for vaccine efficacy and safety.
• Postpone vaccination in individuals with moderate or severe acute illness.
• Screen for contraindications such as previous allergic reactions to the vaccine or its components.

FAQs (Frequently Asked Questions)

Q1: What is the recommended dosage for Haemophilus Type B Conjugate Vaccine + Tetanus Toxoid?

A: For infants, the primary series consists of three doses (0.5 mL each) at 2, 4, and 6 months of age for ActHIB and Hiberix. A booster dose (0.5 mL) is given at 12-15 months.

Q2: Can this vaccine be given to adults?

A: It’s not routinely recommended for healthy adults but may be given to certain at-risk groups, such as those with asplenia, complement deficiencies, or post-HSCT.

Q3: What are the most common side effects?

A: The most common side effects are mild and include injection site reactions (pain, redness, swelling), fever, and irritability.

Q4: Are there any serious side effects?

A: Serious side effects are rare and may include allergic reactions (including anaphylaxis) or seizures (often febrile seizures).

Q5: Can this vaccine be given with other vaccines?

A: Yes, generally, it can be co-administered with other vaccines, but ideally at different injection sites using separate needles and syringes. Consult guidelines regarding specific combinations.

Q6: Is it safe to give this vaccine during pregnancy or breastfeeding?

A: Generally considered safe during both pregnancy and breastfeeding. If there are concerns, discuss with a healthcare professional.

Q7: What should I do if a dose is missed?

A: Consult the recommended catch-up schedules provided by national immunization guidelines or health authorities to determine appropriate actions for missed doses.

Q8: How long does the protection from the vaccine last?

A: The duration of protection varies, and booster doses are necessary to maintain immunity. For most individuals, the primary series plus the booster dose provide long-lasting protection against invasive Hib disease.

Q9: What if my patient has a mild illness, such as a cold?

A: Postpone vaccination for patients with a moderate or severe illness, but mild illnesses like a common cold do not usually contraindicate vaccination.