PHILADELPHIA, PA—The investigational Intradermal (ID) Quadrivalent Inactivated Influenza Vaccine (IIV4-ID) tested in a Phase 3 clinical trial during the 2012–13 influenza season produced antibody responses to B strains that were superior to a licensed split-virion trivalent influenza vaccine (IIV3-ID) containing the alternate strain, and noninferior for the A and matched B strains, results presented at IDWeek 2014 have shown.
“By avoiding vaccine B strain mismatch to the circulating strain, IIV4-ID could improve vaccine efficacy,” reported Geoffrey J. Gorse, MD, of Saint Louis University School of Medicine, St. Louis, MO, and colleagues.
The IIV4-ID vaccine was developed from the IIV3-ID1 vaccine by adding a second B strain hemagglutinin (HA) antigen of the alternate B lineage (Victoria). The study was conducted “to show that the addition of a second B strain does not interfere with the immune response to the other vaccine HA components or alter the safety profile,” said Dr. Gorse.
A total of 1,676 adults aged 18–64 years received IIV4-ID; 837 received the licensed IIV3-ID1, and 847 received the investigational IIV3-ID2. All vaccines were administered intradermally at 9μg HA per virus strain using the BD Soluvia microinjection system.
IIV3-ID1 contained the 2012–13 year B Yamagata lineage strain, and IIV3-ID2 contained the alternate B Victoria lineage. Hemagglutination inhibition (HAI) antibody titers were measured in two thirds of pre-vaccination and Day 28 post-vaccination paired sera. The investigators recorded injection site and systemic reactions and adverse events.
The investigators found that IIV4-ID induced “robust immune responses” in terms of geometric mean HAI titers (GMTs), seroconversion rates (4-fold rise in HAI titer pre- to post-vaccination) and seroprotection rates (HAI titer ≥1:40) for all 4 virus strains.
Immune responses to IIV4-ID, based on GMT ratios and seroconversion rates to each A strain (H1N1 and H3N2) and each B lineage strain (Texas and Brisbane), were statistically noninferior versus the response to control IIV3-ID containing the respective strains . GMT ratios and seroconversion rates to both B strains in IIV4-ID were superior to IIV3-ID without the corresponding B strain.
The IIV4-ID vaccine was well-tolerated and had a safety profile similar to the two IIV3-ID groups. The most commonly reported reactions were pain, pruritus, myalgia, headache, and malaise. Most were mild or moderate and occurred within 3 days of vaccination.
“Quadrivalent intradermal influenza vaccines may reduce the risk of frequent vaccine B strain mismatch with the circulating B strain and reduce morbidity and mortality associated with influenza B virus infection by improving vaccine efficacy” concluded Dr. Gorse.