What it's for (Indications)
- This vaccine is indicated for active immunization against hepatitis A virus (HAV) infection in susceptible individuals aged 12 months and older.
- Hepatitis A is a highly contagious liver infection caused by the hepatitis A virus.
- Vaccination is recommended for individuals at increased risk of HAV infection, including but not limited to, travelers to endemic areas, men who have sex with men, illicit drug users, individuals with chronic liver disease, those receiving clotting factor concentrates, persons working with HAV-infected primates or HAV in research laboratories, and for routine immunization of children and adolescents where public health policy supports broad vaccination efforts.
- The vaccine aims to prevent HAV-associated morbidity and mortality, including fulminant hepatitis and long-term complications.
- Protection is generally conferred within 2-4 weeks after the initial dose, with long-term protection established after a booster dose, providing sustained immunity for many years.
Dosage Information
| Type | Guideline |
|---|---|
| Standard | The primary immunization schedule typically consists of two doses. For individuals aged 12 months to 15 years, a single 0.5 mL dose is administered intramuscularly, followed by a booster dose of 0.5 mL 6 to 12 months later. For individuals aged 16 years and older, a a single 1.0 mL dose is administered intramuscularly, followed by a booster dose of 1.0 mL 6 to 12 months later. The vaccine should be administered into the deltoid region in adults and older children, and into the anterolateral aspect of the thigh in infants and young children. It is crucial to adhere to the recommended dosing schedule to ensure optimal and long-lasting protection against hepatitis A virus infection. While specific brand dosages may vary slightly, the general principle of a primary dose followed by a booster remains consistent. Consult local immunization guidelines for specific age-based recommendations and accelerated schedules if applicable in certain high-risk situations, ensuring proper vaccine storage and administration techniques. |
Safety & Warnings
Common Side Effects
- Commonly reported adverse reactions include local injection site reactions such as pain, tenderness, redness (erythema), and swelling (induration).
- These reactions are generally mild and transient, resolving within 24-48 hours.
- Systemic reactions may include headache, malaise, fatigue, low-grade fever, nausea, vomiting, and loss of appetite.
- Less frequently, myalgia (muscle pain), arthralgia (joint pain), and rash have been reported.
- These systemic effects are typically mild and self-limiting.
- Severe allergic reactions, including anaphylaxis, are exceedingly rare but can occur; appropriate medical treatment and supervision should be readily available during vaccine administration.
- Patients should be advised to report any persistent or severe adverse events to their healthcare provider.
- The overall safety profile of this vaccine is well-established through extensive post-marketing surveillance and clinical trials, demonstrating its high tolerability and minimal risk of serious adverse events.
Serious Warnings
- Black Box Warning: **Serious Warnings and Precautions:** While the Hepatitis A virus HM 175 strain vaccine, like most vaccines, does not carry an FDA-mandated Black Box Warning, several serious considerations warrant careful attention prior to and during its administration to ensure patient safety. Life-threatening allergic reactions, including anaphylaxis, although extremely rare, can occur. Healthcare providers must ensure that appropriate medical treatment, such as epinephrine and resuscitation equipment, is immediately available to manage such events. Individuals with a history of severe allergic reactions to any vaccine component or a previous dose are strictly contraindicated. Syncope (fainting) may occur after vaccination, particularly in adolescents and young adults, potentially leading to injury from falls; therefore, patients should be observed for at least 15 minutes post-vaccination. Immunocompromised individuals, whether due to underlying disease (e.g., HIV infection, leukemia) or immunosuppressive therapy (e.g., high-dose corticosteroids, chemotherapy), may have a diminished immune response to the vaccine and may not be adequately protected; serologic testing post-vaccination may be considered in such cases to assess immune response. The vaccine should under no circumstances be administered intravenously, as this route may lead to severe systemic reactions. Healthcare providers must ensure careful consideration of all known patient allergies, medical history, and current health conditions before vaccination to minimize potential risks and ensure optimal outcomes.
- Prior to administration, healthcare providers should inquire about the patient's medical history, particularly regarding hypersensitivity reactions to previous vaccine doses or components, and any history of bleeding disorders.
- As with all injectable vaccines, appropriate medical treatment and supervision should always be readily available in case of a rare anaphylactic reaction following administration.
- Syncope (fainting) can occur following vaccination, particularly in adolescents and young adults; vaccinees should be observed for approximately 15 minutes post-injection to mitigate injury risk from falls.
- The vaccine should be administered with caution in individuals with thrombocytopenia or any coagulation disorder due to the risk of bleeding or bruising at the injection site following intramuscular injection.
- Immunocompromised individuals, including those receiving immunosuppressive therapy, may have a diminished immune response and may not achieve adequate protection; serologic testing post-vaccination may be considered in such populations.
- Vaccination should be postponed in individuals with moderate or severe acute febrile illness, although minor infections usually do not contraindicate vaccination.
- Pregnant women should receive the vaccine only if clearly needed, and the potential benefits outweigh the potential risks to the fetus, as data on use during pregnancy are limited.
How it Works (Mechanism of Action)
The hepatitis A virus HM 175 strain vaccine (e.g., Epaxal) is an inactivated viral vaccine. It contains purified, inactivated hepatitis A virus particles derived from the HM 175 strain, which are propagated in cell culture, harvested, purified, and then chemically inactivated, rendering them non-infectious but retaining their immunogenic properties. Upon intramuscular administration, these inactivated viral antigens are recognized by the host immune system, primarily by antigen-presenting cells (APCs). This recognition initiates a humoral immune response, stimulating B-lymphocytes to differentiate into plasma cells and produce specific neutralizing antibodies against the hepatitis A virus (anti-HAV antibodies). The vaccine does not cause hepatitis A disease, as the virus is inactivated and incapable of replication. The presence of these antibodies provides active immunity, preventing replication of the live virus upon subsequent exposure and thus protecting against clinical infection and disease. A booster dose enhances the immune response, leading to higher antibody titers and conferring long-term protection, typically lasting for many years.
Commercial Brands (Alternatives)
No other brands found for this formula.