1. Clinical Overview
A single-dose, live attenuated viral vaccine derived from the H2 strain of Hepatitis A virus, propagated in human diploid cells (MRC-5). The 720ELISA unit refers to the antigen content as measured by enzyme-linked immunosorbent assay. It is a lyophilized (freeze-dried) powder requiring reconstitution. It provides active immunization against Hepatitis A virus, a significant cause of infectious hepatitis and jaundice in India, especially in areas with poor sanitation.
| Onset | Duration | Bioavailability |
|---|---|---|
| Protective antibodies typically appear within 15-21 days post-vaccination. | Provides protective immunity for at least 10-15 years, with some studies indicating longer-term protection. Booster doses may be considered after 10 years for high-risk individuals. | Not applicable (N/A) for injectable vaccines. Immunogenicity is the relevant measure, with seroconversion rates >95% in healthy adults and children. |
2. Mechanism of Action
The vaccine contains live Hepatitis A virus (H2 strain) that has been attenuated (weakened) to lose its pathogenicity but retain its immunogenicity. Upon intramuscular administration, the attenuated virus is taken up by antigen-presenting cells. It undergoes limited replication, presenting viral antigens to the immune system. This stimulates a robust humoral (B-cell) and cellular (T-cell) immune response, leading to the production of neutralizing anti-HAV antibodies (mainly IgG) and memory B & T cells.
3. Indications & Uses
- Active immunization against Hepatitis A virus infection in individuals 12 months of age and older.
- Routine childhood immunization in endemic areas like India.
- Pre-travel prophylaxis for non-immune individuals traveling to HAV endemic regions.
4. Dosage & Administration
Adult Dosage: Single dose of 0.5 ml (720 ELISA Units) intramuscularly, preferably in the deltoid region. A booster may be considered after 10 years for sustained travel or occupational risk.
Administration: 1. Store lyophilized vial and diluent at 2°C-8°C. 2. Reconstitute the lyophilized powder with the entire volume of supplied sterile diluent (Water for Injection). 3. Shake well until a clear, colorless to light pink suspension forms. 4. Use immediately after reconstitution (within 1 hour). 5. Administer by deep intramuscular injection. Do not administer intravenously, intradermally, or subcutaneously. 6. Do not mix with any other vaccine or product in the same syringe.
5. Side Effects
Common side effects may include:
- Pain, tenderness, redness, or swelling at the injection site (10-20%).
- Low-grade fever (<38.5°C), malaise, fatigue.
- Headache, irritability in children.
- Loss of appetite, nausea.
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Immunosuppressants (e.g., high-dose corticosteroids, cyclosporine, tacrolimus, chemotherapy) | May diminish the immunologic response to the vaccine, potentially leading to vaccine failure. Avoid vaccination if possible. | Major |
| Other Live Vaccines (e.g., MMR, Varicella, Yellow Fever, Oral Typhoid) | If not administered simultaneously, should be given at least 4 weeks apart to avoid potential interference. | Moderate |
| Immunoglobulins or Blood Products | Administration of immunoglobulins (e.g., for rabies, tetanus) or blood transfusion around the time of vaccination may blunt the immune response. Defer vaccination for at least 3 months after Ig administration, or defer Ig for at least 2 weeks post-vaccination. | Moderate |
7. Patient Counselling
- DO complete the single dose as advised. A booster after 10 years may be discussed with your doctor.
- DO inform your doctor about any immunosuppressive medications or conditions.
- DO report any high fever, severe allergic reaction, or unusual symptoms post-vaccination.
- DONT administer if you have a high fever or severe illness on the day of vaccination (reschedule).
- DONT rub the injection site vigorously.
8. Toxicology & Storage
Overdose: There is no experience with overdose. Administration of more than the recommended dose may increase the frequency and severity of local and systemic adverse reactions.
Storage: Store the lyophilized vial and diluent at +2°C to +8°C (in a refrigerator). Do not freeze. Protect from light. The reconstituted vaccine should be used immediately (within 1 hour) and any unused portion discarded. Do not use if the reconstituted vaccine appears discolored or contains particulate matter.