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

Influvac Tetra is a quadrivalent influenza vaccine used to prevent seasonal influenza infection. It stimulates protective immunity against the four virus strains included in the formulation.

• Seasonal influenza prevention: reduces the risk of laboratory‑confirmed influenza in the general population.
• High‑risk groups: lowers incidence of flu‑related complications in elderly, pregnant women, and persons with chronic medical conditions.
• Pediatric protection: provides immunization for children six months and older, supporting community herd immunity.

• Influvac Tetra contains inactivated influenza virus antigens from two A subtypes and two B lineages. After intramuscular or subcutaneous injection, the antigens are taken up by antigen‑presenting cells, leading to activation of B‑cells and production of strain‑specific neutralising antibodies, as well as T‑cell mediated immunity, thereby establishing active protection against subsequent exposure to the matched influenza viruses.

Vaccination can be associated with transient local and systemic reactions.

Common Side Effects

• Injection site pain: mild to moderate soreness at the injection site.
• Redness or swelling: localized erythema or edema.
• Low‑grade fever: temperature elevation up to 38°C.
• Headache: mild headache within 24 hours.
• Myalgia: muscle aches lasting 1–2 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 within weeks.
• Seizures: febrile seizures in young children.
• Thrombocytopenia: low platelet count observed in isolated cases.

Influvac Tetra should be administered according to national immunisation guidelines and under professional supervision.

• Allergy assessment: avoid if the patient has a known severe allergy to any vaccine component.
• Prior vaccine reaction: defer if a severe reaction occurred after a previous influenza vaccine.
• Immunocompromised status: evaluate risk‑benefit, as response may be reduced.
• Antipyretic use: avoid prophylactic use of analgesics before vaccination; treat symptoms after.
• Storage: 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)

• Live attenuated vaccines: concurrent administration may interfere with immune response.
• High‑dose immunoglobulin therapy: can neutralise vaccine antigens if given within 2 weeks.

Moderate Interactions (Monitor Closely)

• Antiviral medications (e.g., oseltamivir): may reduce vaccine efficacy if started before immunisation.
• Immunosuppressive drugs: may diminish antibody production; timing adjustments may be needed.
• Fever‑reducing agents: may mask early signs of adverse reactions if taken prophylactically.