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

Influvac is a vaccine that targets seasonal influenza viruses to prevent infection.

• Seasonal influenza: reduces the likelihood of acquiring influenza A and B infections.
• High‑risk populations (elderly, chronic disease patients): provides added protection against severe influenza outcomes.
• Community health programs: contributes to herd immunity and lowers overall influenza transmission.

• Influvac contains inactivated viral antigens from the selected influenza B/Austria/1359417/2021‑like strain and influenza A/Vic strain. After intramuscular or subcutaneous injection, these antigens are taken up by antigen‑presenting cells, prompting activation of B‑lymphocytes and production of strain‑specific neutralising antibodies, as well as a T‑cell mediated response, thereby establishing active immunity against the included influenza viruses. The immune memory generated helps the body recognise and rapidly neutralise the virus upon future exposure.

Influvac may be associated with a range of post‑vaccination reactions, most of which are mild and transient.

Common Side Effects

• Injection site pain: mild soreness at the injection site.
• Redness or swelling: localized erythema or edema.
• Low‑grade fever: temperature rise up to 38 °C.
• Headache: mild to moderate head discomfort.
• Myalgia: muscle aches lasting a day or two.
• Fatigue: temporary feeling of tiredness.

Serious or Rare Side Effects

• Anaphylaxis: severe allergic reaction requiring immediate medical attention.
• Guillain‑Barré syndrome: rare neurological disorder with muscle weakness.
• High fever: temperature above 39 °C persisting more than 48 hours.
• Seizures: uncommon convulsive episodes, especially in children.
• Severe local reaction: extensive swelling or necrosis at injection site.

Before administering Influvac, healthcare professionals should consider the following precautions to ensure safe use.

• Allergy assessment: verify no severe allergy to egg protein or vaccine components.
• Post‑vaccination observation: monitor the patient for at least 15 minutes for immediate reactions.
• Pregnancy considerations: discuss benefits and risks with a qualified healthcare provider.
• Immunocompromised patients: vaccine may elicit a reduced immune response.
• Acute illness: defer vaccination until the individual has recovered from moderate or severe febrile illness.
• Store at 2‑8 °C: keep refrigerated, protect from light, do not freeze or shake.

Influvac can interact with certain medical products or therapies; awareness of these interactions helps maintain vaccine effectiveness.

Major Interactions (Avoid)

• Live attenuated vaccines: avoid co‑administration within 4 weeks to prevent interference.
• Immunoglobulin or blood products: may diminish antibody response if given within 2 weeks before or after vaccination.
• Antiviral agents (e.g., oseltamivir): can reduce vaccine efficacy if administered within 48 hours of the vaccine.

Moderate Interactions (Monitor Closely)

• Immunosuppressive therapy: monitor antibody titres as response may be suboptimal.
• Corticosteroids (systemic): may modestly lower immunogenicity, consider timing.
• Febrile illness: vaccination during active fever may increase reactogenicity; assess risk‑benefit.