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

Influvac S Tetra is a quadrivalent influenza vaccine used to prevent seasonal influenza caused by specific B virus strains.

• Seasonal influenza (B strains): reduces the risk of illness, hospitalization, and complications associated with the matched B virus strains.
• High‑risk populations: provides added protection for elderly, immunocompromised, and individuals with chronic health conditions.
• Community health programs: supports public health initiatives aimed at lowering overall influenza transmission rates.

• Influvac S Tetra contains inactivated influenza B virus antigens that are presented to the immune system without causing disease. The antigens are taken up by antigen‑presenting cells, stimulating B‑cell and T‑cell responses that generate strain‑specific neutralizing antibodies. These antibodies persist and provide protective immunity by preventing viral attachment and replication upon subsequent exposure to the corresponding influenza B viruses.

Like other injectable vaccines, Influvac S Tetra may be associated with local and systemic reactions.

Common Side Effects

• Pain at injection site: mild to moderate soreness lasting 1–3 days.
• Redness or swelling: localized erythema that resolves within a few days.
• Low‑grade fever: transient temperature rise, typically below 38.5 °C.
• Headache: mild headache occurring within 24 hours post‑vaccination.
• Muscle aches: transient myalgia lasting up to 48 hours.

Serious or Rare Side Effects

• Anaphylaxis: severe allergic reaction requiring immediate medical attention.
• Guillain‑Barré syndrome: rare neurological disorder reported after influenza vaccination.
• Seizures: uncommon occurrence, especially in individuals with a history of febrile seizures.
• Thrombocytopenia: low platelet count observed in isolated cases.
• Persistent high fever: fever >39 °C lasting more than 72 hours.

Prior to administration, healthcare professionals should consider the following precautions for Influvac S Tetra.

• Contraindication: Do not vaccinate individuals with a known severe allergy to any vaccine component.
• Prior reaction: Defer vaccination in persons who experienced anaphylaxis after a previous influenza vaccine dose.
• Acute illness: Postpone vaccination in patients with moderate or severe acute febrile illness until recovery.
• Immunocompromised status: Assess risk‑benefit in patients receiving immunosuppressive therapy or with compromised immune systems.
• Pregnancy and lactation: Use only if the potential benefit outweighs any potential risk; data are limited.
• Store at 2‑8 °C: keep refrigerated, protect from light, do not freeze or shake the vial.

Influvac S Tetra may interact with certain medications or vaccines; awareness of these interactions helps ensure safety.

Major Interactions (Avoid)

• Live attenuated vaccines: avoid administering within 4 weeks before or after Influvac S Tetra to prevent interference.
• High‑dose corticosteroids: concurrent use may blunt the immune response to the vaccine.
• Immunoglobulin therapy: intravenous immunoglobulin given within 2 weeks can reduce vaccine efficacy.

Moderate Interactions (Monitor Closely)

• Antiviral drugs (e.g., oseltamivir): may be used concurrently but monitor for reduced antibody response.
• Immunosuppressive agents (e.g., methotrexate): continue therapy but assess serologic response after vaccination.
• Fever‑reducing medications (e.g., acetaminophen): may be taken to manage post‑vaccination symptoms without affecting efficacy.