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Quadrivalent influenza vaccine shows superior immunogenicity vs. trivalent vaccine in young children
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Phase 3 study results indicate an inactivated quadrivalent influenza vaccine had superior immunogenicity for an added B strain and comparable immunogenicity for shared strains vs. a trivalent influenza vaccine among children aged 6 to 35 months.
“Annual influenza attack rates are highest in young children, and their rates of complicated influenza that require medical care and hospitalization parallel those in persons older than 65 years,” study researcher Joanne M. Langley, MD, of Dalhousie University in Halifax, Nova Scotia, and colleagues wrote. “Although influenza vaccines are accepted worldwide as the most effective method for preventing influenza, there is a paucity of data on the efficacy of inactivated influenza vaccines in young children.”
To assess vaccine immunogenicity, reactogenicity and safety, researchers conducted a randomized, controlled double blind comparison of a quadrivalent influenza vaccine containing A/California/7/2009(H1N1)pdm09, A/Victoria/361/2011(H3N2), B/Brisbane/60/2008 (Victoria lineage) and B/Hubei-Wujiagang/158/2009 strains and a trivalent influenza vaccine containing the same H1N1, H3N2 and B Yamagata strains but no B Victoria strain. Both vaccines were manufactured by GlaxoSmithKline. Study participants (n = 601) were aged 6 to 35 months.
The lower limit of the two-sided 95% CI for the seroconversion rate ranged from 66.6% to 81.3% and was greater than 40% for all four strains among children who received the quadrivalent vaccine. Seroconversion rate point estimates ranged from 72.2% to 85.9% for each strain.
The lower limit of the two-sided 95% CI of the adjusted geometric mean titer ratio comparing the quadrivalent and trivalent vaccines was greater than 1.5, indicating immunogenic superiority for the additional B Victoria strain in the quadrivalent vaccine. Further, the lower limit of the two-sided 95% CI for the difference in seroconversion rates between the quadrivalent and trivalent vaccines was greater than 10%.
Pain at injection site and irritability were the most commonly reported adverse events during 7 days after vaccination.
“In summary … an inactivated [quadrivalent influenza vaccine] had an immunogenicity that was superior to that of a [trivalent influenza vaccine] for the added B strain and acceptable immunogenicity for the shared strains, with no notable difference in reactogenicity and safety compared to the [trivalent influenza vaccine],” the researchers concluded. – by Amanda Oldt
Disclosure: Langley reports payments and/or grants to her institution from AstraZeneca, Pfizer and Sanofi Pasteur. Langley and the other researchers report financial ties with GlaxoSmithKline, which also funded the study. Please see the full study for a list of all other authors’ relevant financial disclosures.
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