Twinrix Adult is a combination vaccine designed for the prevention of two viral infections: Hepatitis A and Hepatitis B. It is specifically formulated for adults who require protection against both of these liver diseases. Hepatitis A and B are both caused by viruses that can lead to severe liver damage and long-term health complications. Twinrix Adult contains inactivated hepatitis A virus (HAV) and recombinant hepatitis B virus (HBV) antigens, offering a broad spectrum of immunization. The vaccine is administered through an intramuscular injection, providing active immunity against both diseases.

Pharmaceutical Properties:

• Formulation: Twinrix is available as a suspension for injection, typically in a single-dose pre-filled syringe or vial.

• Components:

  • Hepatitis A Virus Inactivated Antigen: 720 ELISA units (for the adult dose).

  • Hepatitis B Virus Recombinant Antigen (HBsAg): 20 micrograms (for the adult dose).

• Adjuvants: The vaccine contains an aluminum hydroxide adjuvant, which enhances the immune response.

The vaccine does not contain live virus; it relies on inactivated virus components to stimulate the immune system to produce protective antibodies.

Indications for Use:

• Primary Prevention of Hepatitis A and B: Twinrix Adult is indicated for the prevention of both hepatitis A and hepatitis B in individuals aged 18 years and older who are at risk of contracting these infections. These include travelers to endemic areas, healthcare workers, individuals with chronic liver disease, and those at high risk due to behavior (such as unprotected sex or drug use).

• Post-exposure Prophylaxis: In certain situations, Twinrix Adult may be used as a preventive measure in individuals who have been exposed to either hepatitis A or B, depending on clinical judgment and exposure history.

Mechanism of Action:

Twinrix Adult works by stimulating the immune system to produce antibodies against both hepatitis A and hepatitis B viruses.

• Hepatitis A Component: The inactivated hepatitis A antigen in the vaccine triggers the immune system to recognize and destroy the virus if the individual is later exposed.

• Hepatitis B Component: The recombinant hepatitis B surface antigen (HBsAg) induces the immune system to produce antibodies against the surface protein of the hepatitis B virus, preventing future infection.

The dual protection offered by Twinrix Adult allows individuals to build immunity against both viruses concurrently, reducing the need for separate vaccinations.

Clinical Protocol in Dubai:

In Dubai, vaccination protocols are based on the guidelines provided by the Dubai Health Authority (DHA). For Twinrix Adult:

1. Administration Schedule:

   • Primary Vaccination: Twinrix is typically administered as a three-dose series:

     • Dose 1: Initial dose

     • Dose 2: 1 month after the first dose

     • Dose 3: 6 months after the first dose.

   • Alternative Schedule: An accelerated schedule may be used for travelers, with doses administered at 0, 7, and 21 days, followed by a booster after 12 months.

2. Post-Vaccination Monitoring: After the first dose, the individual should be observed for 15 minutes for any adverse reactions. It is recommended to monitor for any side effects such as redness or swelling at the injection site, fever, or fatigue.

3. Special Considerations: People with a history of severe allergic reactions to any component of the vaccine or individuals who are immunocompromised should consult their healthcare provider before vaccination. Pregnant or breastfeeding women should discuss potential risks with their doctor.

Other Characteristics:

• Storage: Twinrix Adult should be stored in a refrigerator between 2°C and 8°C. Do not freeze the vaccine.

• Shelf-life: The vaccine has a shelf-life of 36 months from the date of manufacture.

• Contraindications: Twinrix should not be administered to individuals with hypersensitivity to any of its components or to individuals who have a history of severe allergic reactions to a previous dose of the vaccine.

Conclusion:

Twinrix Adult is a comprehensive, combination vaccine that provides dual protection against hepatitis A and B. Its effectiveness in preventing both diseases with a simple three-dose schedule makes it a valuable tool for individuals at risk, particularly in endemic regions like Dubai. The vaccine offers a high level of safety with well-established protocols for administration. As both hepatitis A and B can lead to serious liver disease, immunization with Twinrix Adult plays a vital role in public health, helping reduce the incidence of these infections in at-risk populations.