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

Influvac Tetra is indicated for active immunization against influenza viruses and is used in seasonal flu prevention programs.

• Seasonal influenza: provides protection against circulating influenza A(H1N1), A(H3N2), B/Victoria and B/Yamagata strains.
• Children (6 months to 17 years): reduces the risk of influenza infection and related complications in pediatric populations.
• Adults (18 years and older): lowers incidence of flu and associated hospitalizations in the general adult population.
• High‑risk groups: offers additional protection for elderly, pregnant women and individuals with chronic medical conditions.

• The vaccine contains inactivated, purified antigens from four influenza virus strains. After intramuscular or subcutaneous injection, these antigens are taken up by antigen‑presenting cells, which process and display them to T‑lymphocytes. This triggers a humoral immune response, leading to the production of strain‑specific neutralizing antibodies that can prevent viral entry and replication upon exposure to the corresponding influenza viruses.

Influvac Tetra may be associated with local and systemic reactions following administration.

Common Side Effects

• Injection site pain: mild to moderate soreness at the injection site.
• Redness or swelling: transient erythema or edema around the injection area.
• Low‑grade fever: temperature rise up to 38 °C within 24 hours.
• Headache: mild headache occurring shortly after vaccination.
• Myalgia: muscle aches lasting 1–2 days.
• Fatigue: temporary feeling of tiredness.

Serious or Rare Side Effects

• Anaphylaxis: severe allergic reaction requiring immediate medical attention.
• Guillain‑Barré syndrome: rare neurological disorder that may develop weeks after vaccination.
• Seizures: infrequent occurrence, particularly in children with a history of febrile seizures.
• Severe local reaction: extensive swelling or necrosis at the injection site.
• Thrombotic events: very rare clotting disorders reported post‑vaccination.

Before administering Influvac Tetra, certain precautions should be observed to ensure safety and efficacy.

• Assess allergy: verify no known hypersensitivity to any vaccine component, especially egg protein.
• Defer vaccination: postpone in individuals with moderate or severe acute illness until recovery.
• Immunocompromised patients: evaluate immune status, as response may be reduced.
• Pregnancy and lactation: discuss potential benefits and risks with a healthcare professional.
• Concomitant vaccines: consider spacing with live attenuated vaccines when required.
• Store at 2-8°C: keep refrigerated, protect from light, do not freeze or shake the vial.

Influvac Tetra can interact with certain medications or other vaccines; awareness of these interactions helps optimize immunization outcomes.

Major Interactions (Avoid)

• Live attenuated vaccines: avoid co‑administration within 4 weeks to prevent interference.
• Immunoglobulin therapy: postpone vaccination for at least 3 months after receipt of immune globulin.

Moderate Interactions (Monitor Closely)

• Immunosuppressive drugs: monitor antibody response as effectiveness may be diminished.
• Antipyretics (acetaminophen, ibuprofen): may modestly reduce antibody titers if taken prophylactically.
• Egg allergy: patients with severe egg allergy should be observed closely for reactions.
• Prior influenza vaccination: assess timing to avoid excessive reactogenicity.