INFLUVAC

What it is

INFLUVAC is a purified, inactivated influenza vaccine (surface antigen) containing three influenza strains: A/Missouri/11/2025 (H1N1)pdm09-like virus, A/Singapore/GP20238/2024 (H3N2)-like virus, and B/Austria/1359417/2021 (B/Victoria lineage)-like virus. Each 0.5 mL dose contains 15 micrograms haemagglutinin per each of the above mentioned viral strains, for a combined total amount of 45 micrograms. Each strain has been propagated in fertilised hens' eggs from healthy chickens. INFLUVAC is a clear colourless liquid for injection in pre-filled syringes (glass, type I).

Approved indications

— Prevention of influenza caused by influenza virus, types A and B.

Dosing overview

Adults and children 3 years of age and older receive 0.5 mL. Children from 6 months up to 35 months of age receive a 0.25 mL dose. One dose is sufficient for persons previously exposed to viruses of similar antigenic composition to the strain(s) present in the vaccine. In those with some impairment of immune mechanisms, two doses separated by an interval of at least four weeks are recommended. INFLUVAC should be administered in autumn before the beginning of the influenza season or as required by the epidemiological situation, and vaccination should be repeated every year with an age appropriate dose of vaccine of updated antigen composition.

Key safety warnings

As with all injectable vaccines, appropriate medical treatment and supervision should always be readily available in case of a rare anaphylactic event following the administration of the vaccine. People with egg allergy, including a history of anaphylaxis, can be safely vaccinated unless they have reported a serious adverse reaction to influenza vaccines; egg allergy does not increase the risk of anaphylaxis but anaphylaxis to other components may occur. INFLUVAC should be given with caution to individuals with thrombocytopenia or any coagulation disorder since bleeding may occur following an intramuscular administration to these subjects. Patients with a history of Guillain-Barre syndrome (GBS) with an onset related in time to influenza vaccination may be at increased risk of again developing GBS if given influenza vaccine; while this risk should be weighed against the benefits to the individual patient of influenza vaccination, it would seem prudent to avoid subsequent influenza vaccination in this group.

Contraindications

Hypersensitivity to the active substances, or to any component of the vaccine, except egg proteins. Anaphylaxis following a previous dose of any influenza vaccine. Immunisation should be postponed in patients with an acute febrile illness.

Regulatory history

INFLUVAC Tetra was first listed on the ARTG on 2017-11-02. The TGA approved Influvac Tetra for registration on 1 November 2017. The decision was based on satisfactory quality, nonclinical data, and clinical findings indicating that the benefits of the quadrivalent influenza vaccine outweighed the risks. New ARTG registrations for the trivalent INFLUVAC formulation were listed on 2025-01-21.