Influvac (Influenza Virus B/Austria/1359417/2021-Like Strain (B/Austria/1359417/2021, Bvr-26), Influenza A/Vic)

Influvac is an inactivated influenza vaccine indicated for prevention of influenza infection caused by influenza A and B viruses.

• Seasonal Influenza (A and B): Reduces incidence of laboratory‑confirmed influenza and associated illness.
• High‑Risk Populations (elderly, chronic disease): Lowers risk of severe disease and hospitalization.
• Children (6 months to 17 years): Decreases occurrence of flu and school absenteeism.

• Influvac contains split‑virion antigens from selected influenza A (Victoria lineage) and influenza B (Austria lineage) strains. After intramuscular or subcutaneous injection, the inactivated viral proteins are taken up by antigen‑presenting cells, which process and display hemagglutinin and neuraminidase epitopes to T‑cells. This activates B‑cell differentiation and stimulates production of strain‑specific neutralizing antibodies, establishing active immunity without causing infection.

Influvac, like other inactivated influenza vaccines, may be associated with local and systemic reactions.

Common Side Effects

• Injection site pain: mild to moderate discomfort at the injection site.
• Redness or swelling: transient local inflammation.
• Low‑grade fever: usually resolves within 24‑48 hours.
• Headache or muscle aches: mild and self‑limiting.

Serious or Rare Side Effects

• Anaphylaxis: severe allergic reaction requiring immediate medical attention.
• Guillain‑Barré syndrome: rare neurological disorder reported post‑vaccination.
• High fever or seizures: uncommon but may occur, especially in young children.

Precautions should be observed when administering Influvac.

• Assess allergy history: verify no previous severe reaction to influenza vaccines or egg proteins.
• Delay vaccination: postpone if the individual has an acute moderate or severe illness.
• Monitor after injection: observe for at least 15 minutes for immediate hypersensitivity.
• Avoid in individuals with known hypersensitivity to any vaccine component.
• Pregnancy and lactation: consult a healthcare provider; data are limited.
• Store at 2-8°C: keep refrigerated, protect from light, do not freeze or shake.

Potential drug interactions with Influvac are limited but should be considered.

Major Interactions (Avoid)

• Live vaccines: avoid co‑administration within 4 weeks due to potential interference.
• Immunosuppressive therapy: may reduce vaccine efficacy; consider timing of administration.
• Severe egg allergy: contraindicated if the vaccine contains residual egg protein.
• Antiviral medications (e.g., oseltamivir) taken within 48 hours may blunt immune response.

Moderate Interactions (Monitor Closely)

• Other inactivated vaccines: can be given concomitantly at different sites.
• Immunoglobulin therapy: may interfere with antibody response; schedule appropriately.
• Febrile illness: monitor for increased fever post‑vaccination.