Vaxem10 mcg/0.5 ml

Vaxem is indicated for active immunization of infants and children for the prevention of invasive disease caused by Haemophilus influenzae type b (Hib). This is an FDA-approved, guideline-supported (CDC/ACIP and AAP) routine childhood immunization.

Established indications

• Prevention of Hib meningitis
• Prevention of Hib epiglottitis
• Prevention of Hib bacteremia (invasive bloodstream infection)
• Prevention of other invasive Hib disease, including septic arthritis, cellulitis, and pneumonia caused by Haemophilus influenzae type b

Special/at-risk populations (guideline-supported)

• Unimmunized or incompletely immunized older children and certain adults with functional or anatomic asplenia (including sickle cell disease)
• Individuals with HIV infection
• Recipients of hematopoietic stem cell transplant

Vaxem is given as part of a multi-dose primary series, sometimes combined with other antigens (e.g., as part of a combination pentavalent vaccine) depending on the specific product used. It is not intended for treatment of active Hib infection and does not protect against non-type-b strains of Haemophilus influenzae or against meningitis caused by other organisms.

Each dose of Haemophilus Influenzae Type B Vaccine [Conjugated] contains purified capsular polysaccharide (polyribosylribitol phosphate, PRP) of Haemophilus influenzae type b, covalently conjugated to a carrier protein (such as tetanus toxoid, diphtheria CRM197 protein, or meningococcal outer membrane protein complex, depending on the specific brand/product). Some formulations are supplied as a lyophilized powder for reconstitution with a diluent, while others are supplied as a ready-to-use liquid suspension. Trace amounts of aluminum-based adjuvant, formaldehyde, or preservatives may be present depending on the specific product; consult the specific product's package insert for exact excipients.

Vaxem is a bacterial conjugate vaccine used to actively immunize infants and young children against invasive disease caused by Haemophilus influenzae type b, a bacterium that historically was a leading cause of bacterial meningitis and other serious infections in children under 5 years of age. By conjugating the bacterial capsular polysaccharide to a carrier protein, Vaxem converts a poorly immunogenic antigen (in infants) into one capable of generating a robust, T-cell dependent immune response with immunologic memory, even in very young infants.

Vaxem is administered by intramuscular injection as part of the routine childhood immunization schedule, typically starting at 6 weeks to 2 months of age, with the number of doses depending on the age at which the series is started and the specific product used.

Vaxem belongs to the therapeutic class of bacterial conjugate vaccines, specifically within the broader category of pediatric/childhood immunizing biological agents.

Mechanism of action

Haemophilus Influenzae Type B Vaccine [Conjugated] works by inducing active immunity. The purified capsular polysaccharide (PRP) of Haemophilus influenzae type b is conjugated to a protein carrier, which converts the T-cell-independent polysaccharide antigen into a T-cell-dependent antigen. This conjugation allows even young infants, whose immune systems otherwise respond poorly to plain polysaccharide antigens, to mount a strong anti-PRP antibody (IgG) response along with the generation of immunologic memory (B-cell priming), enabling an effective booster/anamnestic response upon re-exposure or a subsequent dose.

Serum anti-PRP antibody concentrations of ≥0.15 mcg/mL are generally considered protective against invasive Hib disease, with ≥1.0 mcg/mL associated with longer-term protection. Protective antibody levels are typically achieved after completion of the age-appropriate primary series (and booster dose, where applicable) of Haemophilus Influenzae Type B Vaccine [Conjugated].

Vaxem should be administered only by a qualified healthcare professional. Shake the vial or reconstituted vaccine well before use to ensure a uniform suspension, and inspect visually for particulate matter or discoloration; discard if present. If supplied as a lyophilized powder, reconstitute only with the diluent supplied by the manufacturer immediately before use (see Reconstitution). Vaxem may be administered at the same visit as other routine childhood vaccines, using separate syringes and separate injection sites.

Vaxem may be administered simultaneously with other age-appropriate childhood vaccines (e.g., DTaP, IPV, hepatitis B, pneumococcal conjugate, MMR, varicella, rotavirus), provided that separate syringes and separate injection sites are used. Concomitant administration has not been shown to significantly reduce immune response to either Vaxem or the co-administered vaccines in established schedules.

• Immunosuppressive therapy (e.g., corticosteroids, chemotherapy, radiation): may reduce the immune response to Vaxem; vaccination should generally be deferred until therapy is completed where feasible, and immune response should be interpreted with caution in immunosuppressed patients.
• Immune globulin or blood products: concurrent administration is not known to significantly interfere with Vaxem, unlike live-virus vaccines, since Vaxem is not a live vaccine.

There are no well-established clinically significant drug-drug interactions with commonly used medications, since Vaxem is not systemically metabolized in the manner of small-molecule drugs.

Adverse reactions to Vaxem are generally mild and self-limited.

Common (local and systemic)

• Injection site pain, redness, swelling, or warmth
• Fever (usually low-grade)
• Irritability/fussiness
• Drowsiness or decreased activity
• Decreased appetite
• Prolonged crying

Uncommon/rare

• High fever
• Hypotonic-hyporesponsive episode (rare, transient)
• Severe allergic reaction/anaphylaxis (rare; see Contraindications)

Most local and systemic reactions resolve within 1–3 days without specific treatment. Parents/caregivers should seek medical attention for high fever, unusual swelling, difficulty breathing, or signs of a severe allergic reaction.

Vaxem is indicated for infants and young children and is not routinely used in pregnant or breastfeeding women, as invasive Hib disease is rare in healthy adults. Data on use of Vaxem during pregnancy or lactation are limited. If vaccination of an at-risk pregnant or breastfeeding woman (e.g., due to asplenia) is being considered, Vaxem should be used only if clearly needed and if the potential benefit justifies the potential risk; a physician should be consulted before use in pregnancy or lactation.

• Acute illness: Vaccination with Vaxem should generally be deferred in individuals with moderate or severe acute illness (with or without fever) until the condition improves; minor illnesses such as a mild cold do not usually require postponement.
• Bleeding disorders/thrombocytopenia: Use caution and apply firm pressure to the injection site for at least 2 minutes in individuals with a bleeding disorder or on anticoagulant therapy, due to risk of bleeding at the intramuscular injection site.
• Altered immunocompetence: Immune response to Vaxem may be diminished in individuals with immunosuppression; vaccination is still generally recommended in this group but response may be attenuated.
• Syncope: Vasovagal syncope can occur after vaccination; observe patients for a short period after administration where feasible.
• Limitations: Vaxem protects only against Haemophilus influenzae type b; it does not protect against non-type-b strains of H. influenzae, or against meningitis or other invasive disease caused by other organisms such as Neisseria meningitidis or Streptococcus pneumoniae.
• As with any vaccine, Vaxem may not fully protect all recipients.

There is no established data on overdose with Vaxem, and inadvertent administration of an extra dose or a larger-than-recommended volume is uncommonly reported in clinical practice. If an overdose or inadvertent extra dose of Vaxem is suspected, seek immediate medical attention or contact a physician, hospital emergency department, or poison control center for evaluation; the child should be monitored for any unusual local or systemic reaction.

Store Vaxem refrigerated at 2°C to 8°C (36°F to 46°F). Do not freeze; discard the vaccine if it has been exposed to freezing temperatures. Protect from light. If supplied as a lyophilized powder with a separate diluent, store both components as directed by the manufacturer, and use the reconstituted vaccine promptly (typically within 24 hours) if not used immediately. Keep out of reach of children.

Pediatric use

Vaxem is specifically formulated and indicated for use in infants and children, typically starting as early as 6 weeks of age through 59 months (5 years), per the routine immunization schedule (see Dosage and Administration). Use in children older than 59 months is generally not recommended except in specific high-risk groups (e.g., functional/anatomic asplenia including sickle cell disease, HIV infection, hematopoietic stem cell transplant recipients), where catch-up or supplemental dosing may be advised by a physician.

Elderly/adult use

Vaxem is not part of routine adult immunization. Safety and efficacy in the general adult population have not been established; use in adults is generally limited to specific high-risk indications under medical supervision.

Renal/hepatic impairment

No specific dose adjustment of Vaxem is established for renal or hepatic impairment, as the vaccine is not systemically metabolized in the manner of small-molecule drugs; however, immune response may be assessed on a case-by-case basis in patients with significant organ dysfunction or immunocompromise.

Vaxem is not a continuous treatment but a scheduled immunization series. The full course (primary series plus booster dose, where applicable, based on age at first dose) should be completed according to the recommended schedule to achieve and maintain adequate protective antibody levels. Doses should not be skipped, and the series should not be restarted from the beginning even if there is a delay between doses — the next dose in the series should simply be given as soon as feasible.

Certain formulations of Vaxem are supplied as a lyophilized (freeze-dried) powder that must be reconstituted immediately before administration using only the specific liquid diluent or companion vaccine component supplied by the manufacturer for that product. Reconstitute by adding the entire contents of the diluent vial/syringe to the vial of lyophilized powder and shake well until a uniform, slightly turbid white suspension is obtained. Inspect the reconstituted vaccine visually for particulate matter or discoloration before use, and discard if present. Use the reconstituted vaccine promptly; do not store for extended periods (follow the specific product's package insert for the exact permissible time window). Do not use a diluent or vaccine component from a different manufacturer or product for reconstitution.

Haemophilus Influenzae Type B Vaccine [Conjugated] is classified as a bacterial polysaccharide-protein conjugate vaccine, within the general class of pediatric immunizing biological agents/vaccines.

Haemophilus Influenzae Type B Vaccine [Conjugated] induces active, T-cell-dependent immunity against Haemophilus influenzae type b by presenting its capsular polysaccharide (PRP) antigen conjugated to a carrier protein, which enhances immunogenicity and immunologic memory formation even in young infants, resulting in production of protective anti-PRP IgG antibodies.

Vaxem is specifically indicated for the pediatric population and forms part of the routine childhood immunization schedule recommended by the CDC/ACIP, WHO, and AAP. It is typically first given at 6 weeks to 2 months of age, with the primary series and booster completed according to the age-based schedule described in Dosage and Administration. Safety and efficacy of Vaxem have not been established for use in healthy children older than 59 months (5 years) of age, except in specific high-risk groups as advised by a physician. Common adverse effects in this population include local injection site reactions, low-grade fever, and transient irritability, which are expected and self-limited (see Side Effects).