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 quadrivalent subunit influenza vaccine used to prevent seasonal influenza infections.

• Seasonal influenza (A and B): reduces the incidence of laboratory‑confirmed influenza and associated complications.
• High‑risk groups (elderly, chronic disease patients): provides protective immunity to lower hospitalization rates.
• Children ≥ 6 months: induces antibody response to prevent flu‑related illness in pediatric populations.

• Influvac Sub-Unit Tetra contains purified hemagglutinin antigens from four influenza virus strains. After intramuscular or subcutaneous injection, the antigens are taken up by antigen‑presenting cells, stimulating B‑cell production of strain‑specific antibodies and generating memory cells that confer protection against subsequent exposure to the matched influenza viruses.

Common and rare adverse reactions may occur after administration of Influvac Sub-Unit Tetra.

Common Side Effects

• Injection site pain: mild to moderate discomfort at the injection site.
• Redness or swelling: localized erythema or edema.
• Fever: transient low‑grade temperature rise.
• Headache: mild headache within 24 hours.
• Myalgia: muscle aches lasting up to two days.
• Fatigue: temporary tiredness post‑vaccination.

Serious or Rare Side Effects

• Anaphylaxis: severe allergic reaction requiring immediate medical attention.
• Guillain‑Barré syndrome: rare neurological disorder reported after influenza vaccination.
• Seizures: infrequent convulsive episodes.
• High‑grade fever: persistent fever above 39 °C.

Prior to vaccination, healthcare professionals should consider the following precautions for Influvac Sub-Unit Tetra.

• Pregnancy: safety not established; vaccinate only if benefits outweigh potential risks.
• Age: indicated for individuals 6 months of age and older.
• Allergy: avoid in persons with known hypersensitivity to any vaccine component.
• Immunocompromised: vaccine may elicit a reduced immune response; assess benefit‑risk.
• Concurrent vaccines: may be administered with other inactivated vaccines at separate sites.
• Store at 2‑8 °C: keep refrigerated, protect from light, do not freeze or shake.

Potential drug interactions should be reviewed before administering Influvac Sub-Unit Tetra.

Major Interactions (Avoid)

• Severe hypersensitivity to a previous dose: contraindicates further administration.
• Live attenuated vaccines given concurrently: may interfere with immune response; avoid simultaneous use.

Moderate Interactions (Monitor Closely)

• Antiviral agents (e.g., oseltamivir) started within 48 hours of vaccination: may reduce immunogenicity.
• Immunoglobulin therapy or blood products administered within 3 weeks: may diminish antibody response.
• High‑dose corticosteroids or other immunosuppressants: may lower vaccine efficacy.