Influvac Sub-Unit Tetra (B/Phuket/3073/2013-Like Virus (B/Phuket/3073/2013, Wild Type), Influenza Virus B/Austria/1359417/202)

Influvac Sub-Unit Tetra is a subunit influenza vaccine used to protect against influenza virus infections, primarily targeting the B lineage.

• Influenza B infection: reduces the risk of laboratory‑confirmed influenza B disease.
• Seasonal influenza (A and B strains): contributes to overall seasonal flu prevention when administered as part of a tetravalent formulation.
• High‑risk populations (elderly, chronic disease patients, pregnant women): provides added protection to groups more likely to experience severe flu complications.

• The vaccine contains purified hemagglutinin antigens from selected influenza B virus strains. After intramuscular or subcutaneous injection, these antigens are taken up by antigen‑presenting cells, stimulating B‑cell and T‑cell responses that lead to the production of strain‑specific antibodies, thereby conferring active immunity against subsequent exposure to the matching influenza viruses.

Common Side Effects

• Injection site pain: mild to moderate discomfort at the injection site.
• Redness or swelling: localized erythema or edema.
• Low‑grade fever: transient temperature rise within 24‑48 hours.
• Headache: mild headache following vaccination.
• Myalgia: muscle aches that resolve spontaneously.
• Fatigue: temporary tiredness after immunisation.

Serious or Rare Side Effects

• Anaphylaxis: severe allergic reaction requiring immediate medical attention.
• Guillain‑Barré syndrome: rare neurological disorder potentially linked to vaccination.
• Seizures: infrequent occurrence, especially in children with a history of febrile seizures.
• Severe local reaction: extensive swelling or necrosis at the injection site.
• Thrombotic events: extremely rare clotting complications.
• Acute respiratory distress: rare severe respiratory compromise.

Before administering Influvac Sub-Unit Tetra, consider the following precautions:

• Allergy assessment: avoid in individuals with known severe allergy to any vaccine component.
• Acute illness: defer vaccination in persons with moderate or severe febrile illness.
• Immunocompromised patients: evaluate risk‑benefit, as response may be reduced.
• Pregnancy and lactation: discuss potential benefits and unknown risks with a healthcare professional.
• Concomitant vaccines: follow recommended intervals when co‑administering other vaccines.
• Store at 2-8°C: keep refrigerated, protect from light, do not freeze or shake.

Vaccines may interact with other agents that modify the immune response.

Major Interactions (Avoid)

• Concurrent administration of another influenza vaccine: may increase reactogenicity.
• High‑dose immunoglobulin therapy within 3 weeks: can diminish vaccine efficacy.

Moderate Interactions (Monitor Closely)

• Antipyretics (e.g., acetaminophen, ibuprofen) taken prophylactically: may slightly reduce antibody response.
• Systemic corticosteroids: may blunt immunogenicity if used at high doses.
• Live attenuated vaccines given within 4 weeks: monitor for overlapping adverse events.