Last reviewed 2026-04-22 · How we verify

Standard Dose Quadrivalent Influenza Vaccine

The vaccine stimulates the immune system to produce antibodies against four strains of influenza virus, providing protection against seasonal flu infection.

The vaccine stimulates the immune system to produce antibodies against four strains of influenza virus, providing protection against seasonal flu infection. Used for Seasonal influenza prevention in adults and children ≥6 months of age.

At a glance

Mechanism of action

Quadrivalent influenza vaccines contain inactivated viral antigens from four influenza strains (two A subtypes and two B lineages). When administered, these antigens trigger both humoral and cellular immune responses, leading to the production of strain-specific antibodies and memory B cells. This immune priming enables rapid recognition and neutralization of circulating influenza viruses, reducing infection risk and disease severity.

Approved indications

• Seasonal influenza prevention in adults and children ≥6 months of age

Common side effects

• Injection site pain, erythema, or swelling
• Myalgia
• Headache
• Fatigue
• Low-grade fever

Key clinical trials

• Influenza Vaccination Strategy for Patients With Hematologic Malignancy (PHASE3)
• A Study to Evaluate the Intratumoral Influenza Vaccine Administration in Patients With Breast Cancer (PHASE1)
• High vs. Standard Dose Influenza Vaccine in Adult SOT Recipients (PHASE2)
• Study on a High-Dose Quadrivalent Influenza Vaccine Compared With Standard-Dose Quadrivalent Influenza Vaccine in Children 6 Months Through 35 Months of Age (PHASE3)
• High vs. Standard Dose Influenza Vaccine in Lung Allograft Recipients (PHASE2)
• Randomized Influenza Vaccine Evaluation of Immune Response (PHASE4)
• Study to Assess the Immune Response and the Safety Profile of a High-Dose Quadrivalent Influenza Vaccine (QIV-HD) Compared to a Standard-Dose Quadrivalent Influenza Vaccine (QIV-SD) in Taiwanese Adults 65 Years of Age and Older (PHASE3)
• Study to Assess the Immune Response and the Safety Profile of a High-Dose Quadrivalent Influenza Vaccine (QIV-HD) Compared to a Standard-Dose Quadrivalent Influenza Vaccine (QIV-SD) in Japanese Adults 60 Years of Age and Older (PHASE3)

Primary sources

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