VAXIGRIP TETRA

Indications

• Prevention of influenza virus infection
• Reduction of the severity of influenza illness
• Protection for high-risk groups against influenza complications

Dosage

Children: Refer to the BNF for Children for specific dosing recommendations for paediatric patients based on age and health status.

Adults: Refer to the BNF for specific dosing recommendations for adult patients based on the type of vaccine and individual health status.

Mechanism of action

Influenza vaccines stimulate the immune system to produce antibodies against the influenza virus. When the body is exposed to the virus, these antibodies help to prevent infection or mitigate the severity of the disease. The vaccines may contain inactivated virus or live attenuated virus, depending on the formulation.

Pharmacodynamics

Upon administration of the influenza vaccine, the immune system recognizes the viral antigens and generates a specific immune response. This response includes the production of antibodies, primarily immunoglobulin G (IgG), which can neutralize the virus and prevent its replication. The response varies based on individual health status and age.

Pharmacokinetics

The pharmacokinetics of influenza vaccines vary by type. After intramuscular or subcutaneous administration, the vaccine components are absorbed into the systemic circulation, leading to the production of antibodies. Peak antibody levels typically occur within 2 to 4 weeks after vaccination. The half-life of antibodies can vary, but they generally persist for several months, providing immunity against future infections.

Interactions

• normal immunoglobulin + influenza vaccine live: Unknown (decreases efficacy)

Pregnancy

Influenza vaccination is recommended during pregnancy, especially in the second and third trimesters, as it protects both mother and fetus.

Breast-feeding

Influenza vaccination is safe during breastfeeding and provides passive immunity to the infant.

Storage

Influenza vaccines should be stored in a refrigerator at 2 to 8 degrees Celsius. Do not freeze.

Indications

• Prevention of infectious diseases such as measles, mumps, rubella, hepatitis B, influenza, and human papillomavirus (HPV)
• Travel vaccinations for diseases endemic to certain regions
• Vaccination for at-risk populations, such as those with compromised immune systems or specific occupational exposures

Dosage

Children: Dosage varies by vaccine type and age; refer to the BNF for Children for specific dosing information.

Adults: Dosage varies by vaccine type and indication; refer to specific guidelines for each vaccine.

Mechanism of action

Vaccines work by mimicking an infection. They introduce a harmless component of a pathogen (antigen) to the immune system, prompting the body to produce an immune response. This includes the generation of antibodies and memory cells that provide long-term immunity. Upon subsequent exposure to the actual pathogen, the immune system is primed to respond more rapidly and effectively.

Pharmacodynamics

The pharmacodynamics of vaccines involves the activation of both humoral and cellular immunity. Vaccines stimulate B cells to produce antibodies against the pathogen, while T cells are activated to destroy infected cells. This dual response helps to establish immunological memory, which enables a faster and more robust response upon re-exposure to the pathogen.

Pharmacokinetics

Vaccines are administered via various routes, including intramuscular, subcutaneous, and oral. After administration, the antigens are presented to antigen-presenting cells, which activate T cells and stimulate B cell proliferation and differentiation. The half-life of vaccine-induced immunity varies depending on the type of vaccine, with some providing lifelong immunity and others requiring booster doses to maintain protection.

Contra-indications

• Severe allergic reaction (anaphylaxis) to a component of the vaccine
• Severe immunocompromised state for live attenuated vaccines

Adverse effects

• Local reactions at the injection site (pain, redness, swelling)
• Fever
• Fatigue
• Headache
• Muscle pain
• Joint pain
• Nausea

Interactions

• Immunosuppressive medications may reduce vaccine efficacy
• Concurrent administration of some vaccines may require spacing to optimize immune response

Precautions

• History of allergic reactions to vaccines or vaccine components
• Pregnancy (specific vaccines may be contraindicated)
• Moderate to severe acute illness with or without fever

Pregnancy

Consult healthcare provider. Some vaccines are contraindicated during pregnancy, while others are recommended.

Breast-feeding

Generally considered safe, but consult healthcare provider regarding specific vaccines.

Storage

Store in a refrigerator at 2-8°C. Do not freeze. Protect from light.

Formulations

• Liquid suspension for injection
• Lyophilized powder for reconstitution

Indications

• Influenza
• HIV/AIDS
• Hepatitis B and C
• Herpes simplex virus infections
• Cytomegalovirus infections
• COVID-19
• Respiratory syncytial virus infections

Dosage

Children: Refer to specific antiviral agents for dosing guidance.

Adults: Refer to specific antiviral agents for dosing guidance.

Mechanism of action

Viruses infect host cells by attaching to specific receptors on the cell surface. Once inside, they hijack the host cell's machinery to replicate their genetic material and produce viral proteins. New viral particles are assembled and released from the host cell, often destroying the cell in the process. The specific mechanism can vary depending on the virus type, including integration into the host genome in retroviruses or utilizing specific pathways for replication.

Pharmacodynamics

The pharmacodynamics of antiviral agents depend on the specific virus and the mechanism of action. Antiviral drugs may inhibit viral entry into host cells, block viral replication, or prevent the assembly of new virions. The effectiveness of antiviral therapy often relates to the stage of viral replication and the immune response of the host.

Pharmacokinetics

Pharmacokinetics of antiviral drugs varies widely based on the specific medication used. Generally, antiviral agents are absorbed through the gastrointestinal tract and distributed throughout the body. They may undergo hepatic metabolism and are often excreted through the kidneys. The half-life of these drugs can range from a few hours to several days, influencing dosing schedules.