Hepatitis B adult vaccine
Hepatitis B adult vaccine
Generic Name
Hepatitis B adult vaccine
Mechanism
- Recombinant DNA HBsAg is produced in yeast (Saccharomyces cerevisiae) cells and purified for injection.
- Upon intramuscular administration, HBsAg is taken up by antigen‑presenting cells (macrophages and dendritic cells).
- MHC‑II presentation activates CD4⁺ helper T cells, which provide cytokine help to B cells.
- B cells differentiate into plasmablasts and produce anti‑HBs antibodies; these persist as humoral memory and confer long‑term protection.
- The vaccine does not contain viral DNA or capsids, eliminating risk of viral replication.
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Pharmacokinetics
| Parameter | Feature |
| Absorption | Absorbed slowly at the injection site; antigen delivered to draining lymph nodes |
| Distribution | Limited systemic distribution; local trafficking to sentinel lymph nodes |
| Half‑life | Antigen is processed rapidly; humoral response peaks within weeks, memory persists for decades |
| Metabolism | Non‑enzymatically degraded into amino acids; not hepatically metabolized |
| Excretion | Metabolites excreted via renal and biliary routes along with protein catabolism |
> *Because HBsAg is a protein antigen, its pharmacokinetic profile is governed by immune uptake rather than conventional absorption‑distribution‑metabolism–excretion dynamics.*
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Indications
- Primary prophylaxis of HBV infection in adults (≥18 y) who are HBsAg‑negative.
- Occupational exposure prevention (health‑care workers, laboratory staff, first responders).
- Travel medicine for individuals going to endemic regions.
- Post‑exposure prophylaxis (PEP) in adults exposed to HBV‑positive blood or bodily fluids.
- Immunization of household contacts of chronic HBV patients.
- Patients with chronic liver disease or at high risk for HBV flare (e.g., cirrhosis, hepatitis C co‑infection).
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Contraindications
| Category | Details |
| Absolute contraindication | Known hypersensitivity to any vaccine component (e.g., gelatin, yeast). |
| Relative contraindications | Severe acute illness; uncontrolled trauma; active, severe, or untreated immunosuppression (e.g., HIV with CD4 < 200 cells/µL) – consider vaccination timing |
| Pregnancy | No evidence of teratogenicity; generally considered safe; avoid in lactating mothers with eczema or allergic compromise. |
| Allergic reaction to previous doses | Repeat dose usually contraindicated; consult allergist. |
| Autoimmune disease | Use with caution; monitor for flare; may require systemic steroid cover in selected cases. |
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Dosing
| Schedule | Dosage | Schedule | Comments |
| Standard | 20 µg HBsAg (1 mL) per dose | 0 , 1, 6 months (3‑dose series) | Recommended for general adult immunization. |
| Accelerated | 20 µg HBsAg (1 mL) | 0 , 1, 2, 12 weeks | For high‑risk workers or immediate protection; reduces immunization gap. |
| Booster | 20 µg HBsAg (1 mL) | Single dose | For adults previously vaccinated >10 y ago or with low anti‑HBs titers. |
• Route: Intramuscular (deltoid preferred; gluteus maximus if not available).
• Timing for PEP: Ideally within 24 h of exposure; if delayed, vaccinate as soon as possible (≤7 days).
• Co‑administration: Can be given with other vaccines (influenza, Tdap) unless contraindications exist.
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Monitoring
- Seroconversion: 1‑3 months post‑final dose; anti‑HBs titer > 10 IU/L → considered protected.
- Post‑exposure: Follow serial anti‑HBs levels at 30 days; placebo‑managed patients should receive HBIG if necessary.
- Adverse events: Record in electronic health record; adverse‑event reporting to VICP/CDC for national surveillance.
- Specialized cases: In immunocompromised adults, repeat vaccination 5–10 days later to boost response; monitor anti‑HBs titers 1 month after revaccination.
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Clinical Pearls
- Accelerated schedule is 100 % effective: Use for health‑care workers or individuals in high‑risk settings where time is limited.
- Single‑dose “catch‑up” for adults: If an adult is <95 % seroprotected and the vaccination series is incomplete, a one‑dose booster can suffice, contingent on detectable pre‑existing anti‑HBs levels.
- Co‑inject with HBStype: Co‑administer with hepatitis B surface antibody screening; if anti‑HBs < 10 IU/L post‑vaccination, consider a fourth dose.
- Pregnancy & breastfeeding: There is no contraindication; safe in lactation, but avoid in patients with acute hepatic disease or uncontrolled sepsis.
- Immunocompromised: For solid‑organ recipients, the standard schedule may require an extra dose or 10‑microgram/dose regimen; perform serologic checks at 1 month.
- Adjuvant considerations: Some vaccine brands (e.g., Engerix‑B) contain aluminum hydroxide as an adjuvant; caution in patients with hypersensitivity to aluminum or with certain autoimmune conditions.
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• *This drug card consolidates evidence‑based information for physicians, pharmacists, and medical trainees. For detailed guidelines, refer to the CDC’s Hepatitis B Vaccination Recommendations and WHO’s Hepatitis Vaccine Handbook.*