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 that stimulates immunity against seasonal influenza viruses.

• Seasonal influenza: provides active immunity against the four virus strains contained in the vaccine, reducing the incidence of infection.
• High‑risk populations (elderly, chronic disease patients, pregnant women): helps lower the risk of severe influenza complications and related hospitalizations.
• Healthcare workers and caregivers: contributes to occupational protection and decreases transmission of influenza within clinical and community settings.

• Influvac Tetra contains purified hemagglutinin antigens from two influenza A subtypes and two influenza B lineages. After intramuscular or subcutaneous injection, antigen‑presenting cells process the proteins and present them to helper T cells, activating B cells to produce strain‑specific antibodies against hemagglutinin and neuraminidase, thereby establishing humoral immunity that neutralizes the corresponding influenza viruses.

Following vaccination, Influvac Tetra may be associated with 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 up to 38 °C.
• Headache: transient mild headache.
• Myalgia or fatigue: muscle aches and tiredness.

Serious or Rare Side Effects

• Anaphylaxis: severe allergic reaction requiring immediate medical attention.
• Guillain‑Barré syndrome: rare neurological disorder that may develop within weeks.
• High‑grade fever or seizures: uncommon systemic reactions that need urgent care.

Prior to administration, consider the following precautions to ensure safe use of Influvac Tetra.

• Screen for severe allergy: avoid in individuals with known hypersensitivity to any vaccine component.
• Defer vaccination during acute illness: postpone in persons with moderate or severe fever or infection.
• Pregnancy considerations: use only if potential benefits outweigh uncertain risks, as data are limited.
• Immunocompromised patients: vaccine may elicit reduced immune response; monitor effectiveness.
• Age restriction: not approved for children younger than 6 months of age.
• Store at 2‑8 °C: keep refrigerated, protect from light, do not freeze or shake.

Influvac Tetra may interact with other medical products; the following interactions should be noted.

Major Interactions (Avoid)

• Live vaccines: avoid co‑administration with live attenuated influenza vaccine or other live vaccines within a 4‑week interval.
• Immunoglobulin therapy: concurrent administration may diminish vaccine efficacy; avoid within 2 weeks of each other.

Moderate Interactions (Monitor Closely)

• Antipyretic or analgesic use: may mask post‑vaccination fever or pain; use as needed.
• Immunosuppressive drugs: may reduce antibody response; consider serologic monitoring.
• Blood products or plasma: transfusion within 48 h may interfere with immune response; schedule appropriately.