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Pharmacology: Pharmacodynamics: Mechanism of action: Influvac Tetra provides active immunization against four influenza virus strains: an A/(H1N1) strain, an A/(H3N2) strain, and two B strains (one from each lineage; B/(Victoria) and B/(Yamagata)). Influvac Tetra, manufactured according to the same process as trivalent influenza vaccine Influvac, induces humoral antibodies against the haemagglutinins. These antibodies neutralize influenza viruses.
Specific levels of hemagglutination-inhibition (HI) antibody titer post-vaccination with inactivated influenza virus vaccines have not been correlated with protection from influenza illness but the HI antibody titers have been used as a measure of vaccine activity.
An immune response is generally obtained within 2 to 3 weeks. The duration of postvaccinal immunity to homologous strains or to strains closely related to the vaccine strains varies but is usually 6-12 months.
Pharmacodynamic effects: Efficacy of Influvac Tetra in children 6 – 35 months of age: The efficacy of Influvac Tetra was evaluated in a randomized, observer-blind, non-influenza vaccine-controlled study (INFQ3003) conducted during 3 influenza seasons 2017 to 2019 in Europe and Asia. Healthy subjects aged 6 - 35 months received two doses of Influvac Tetra (N=1005) or non-influenza control vaccine (N=995) approximately 28 days apart. The efficacy of Influvac Tetra was assessed for the prevention of reverse transcription polymerase chain reaction (RT-PCR)-confirmed influenza A and/or B disease due to any influenza strain. All RT-PCR-positive specimens were further tested for viability in cell culture and to determine whether the circulating viral strain matched those in the vaccine. (See Table 1.)
Click on icon to see table/diagram/imageImmunogenicity of Influvac Tetra compared to trivalent Influvac: Clinical studies performed in adults of 18 years of age and older (INFQ3001) and children of 3 to 17 years of age (INFQ3002) assessed the safety and immunogenicity of Influvac Tetra and its non-inferiority to trivalent influenza vaccine Influvac for the post-vaccination HI Geometric mean antibody titer (GMT).
In both studies the immune response elicited by Influvac Tetra against the three strains in common was non-inferior to trivalent influenza vaccine Influvac. Influvac Tetra elicited a superior immune response against the additional B strain included in Influvac Tetra compared to trivalent influenza vaccine Influvac.
Adults 18 years of age and older: In clinical study INFQ3001, 1,535 adults of 18 years of age and older received a single dose of Influvac Tetra and 442 subjects received a single dose of trivalent Influvac: (See Table 2.)
Click on icon to see table/diagram/imagePediatric population: Children 3-17 years of age: In clinical study INFQ3002, 402 children of 3 to 17 years of age received one or two doses of Influvac Tetra and 798 children received one or two doses of trivalent Influvac based on their influenza vaccination history. (See Table 3.)
Click on icon to see table/diagram/imageChildren 6 months - 35 months of age: In clinical study INFQ3003 the immunogenicity of Influvac Tetra was evaluated in terms of seroconversion rates across 3 influenza seasons. (See Table 4.)
Click on icon to see table/diagram/imagePharmacokinetics: Not applicable.
Toxicology: Preclinical safety data: Non-clinical data revealed no special hazard for humans based on conventional studies of repeat dose and local toxicity, reproductive and developmental toxicity and safety pharmacology studies.
