SUMMIT, N.J., Aug. 30, 2019 /PRNewswire/ -- Seqirus, a global leader in influenza prevention, today presented data at the Options for the Control of Influenza (OPTIONS X) Conference in Singapore from clinical studies demonstrating the ability of a MF59® adjuvanted influenza vaccine to increase immune responses when used in both seasonal and pandemic influenza vaccines, across pediatric and adult populations.1,2,3,4
Seasonal Protection
An adjuvant such as MF59® is added to an influenza vaccine with the intended purpose of creating a strong, broad, and durable immune response.5 As detailed in the data presentations today, a quadrivalent, adjuvanted seasonal influenza vaccine:
- Induced a higher immune response upon two revaccination studies as demonstrated for both homologous and heterologous strains in children (6 months to 72 months old) compared to a non-adjuvanted influenza vaccine1
- Produced a greater magnitude of cross-reactive antibody responses compared to a non-adjuvanted influenza vaccine in children with lower preexisting antibody titers, regardless of age (6 months through 23 months old or 36 months through 71 months old) or vaccination history2
The studies were conducted during influenza seasons characterized by antigenic drift, or small genetic mutations that accumulate in the circulating virus over time,6 in the influenza A (H3N2) strain.7,8,9 Antigenic drift can cause a strain mismatch between the circulating virus and the influenza vaccine virus strains designated by the World Health Organization (WHO).6,9 Adjuvanted influenza vaccines have demonstrated the ability to enhance the production of immune cells in the body and generate more cross-reactive antibodies against influenza virus strains that have mutated, compared to non-adjuvanted standard dose vaccine.1,2,10,11
"These studies show that the use of MF59® adjuvant technology can broaden the immune response against influenza viruses," said Russell Basser, MD, Chief Scientist and Senior Vice President of Research and Development at Seqirus. "At Seqirus, we're dedicated to researching and developing vaccines designed to transform approaches to influenza prevention."
MF59® adjuvanted seasonal influenza vaccines have a demonstrated safety profile, with more than 100 million doses distributed since the trivalent formulation was first licensed in 1997.12
Pandemic Protection
MF59® adjuvant, combined with a cell-based pandemic influenza A (H5N1) vaccine candidate, was found to induce antibodies that may enhance the immune response against heterologous A (H5N1) strains.3,4 In the presented clinical studies that examined a first-of-its-kind A (H5N1) adjuvanted,13 cell-based pandemic influenza vaccine, results showed:
- Increased immune responses against heterologous A (H5N1) strains in adults (18 to < 65 years old) and the elderly (≥ 65 years of age) with a full-dose vaccination (7.5 μg hemagglutinin (HA) of H5N1 with 0.25 mL MF59® for a total injection volume of 0.5 mL)3,14
- Increased immune responses against heterologous A (H5N1) strains in children (6 months to £ 17 years old) with a full-dose vaccination (7.5 μg hemagglutinin (HA) of H5N1 with 0.25 mL MF59® for a total injection volume of 0.5 mL)4,14
Influenza A (H5N1) viruses have high pandemic potential; therefore, vaccines need to be rapidly produced when these strains emerge.15 Pandemic influenza vaccines with MF59® adjuvant require less antigen per vaccine dose compared to most seasonal formulations, allowing for more rapid vaccine availability.15,16 MF59® adjuvanted vaccine is an important part of pandemic preparedness planning as it has been shown to generate high levels of cross-reactive antibodies against five separate genetic clades of A (H5N1) virus in both pediatric and adult populations, highlighting the potential public health benefits of pandemic vaccine stockpiling.3,4,15
"The data presented at OPTIONS X complement previous clinical studies that emphasize the important role of innovative technologies, such as the MF59® adjuvant, in broadening and enhancing the immune response against evolving seasonal and pandemic influenza viruses," said Anjana Narain, Executive Vice President at Seqirus. "As part of our role on the front line of influenza prevention, we're committed to developing advanced technologies and vaccines that can help provide seasonal protection as well as provide a rapid production response during a pandemic outbreak."
An influenza pandemic requires rapid production of very large quantities of vaccine, and Seqirus has the capability to enhance vaccine production by using cell-based vaccine manufacturing in the event of a pandemic as a result of its public-private partnership with the U.S. Biomedical Advanced Research and Development Authority (BARDA).17,18,19 The U.S. Food and Drug Administration (FDA) recently accepted the supplemental Biologics License Application (sBLA) for the first ever adjuvanted, cell-based influenza vaccine against the influenza A (H5N1) strain.13
About the Studies
MF59®-Adjuvanted Seasonal Influenza Vaccine in the Pediatric Population
Two revaccination extension studies were conducted in children aged 6 months to 72 months who participated in a parent efficacy study (NCT01964989) and received a primary influenza vaccination with an adjuvanted quadrivalent influenza vaccine (aQIV) or non-adjuvanted vaccine. The immune response against vaccine-homologous strains was assessed in all study subjects and a subset of patients were assessed against vaccine-heterologous strains. The reactogenicity and safety of the study vaccines were assessed in all study subjects. Rates of adverse events after revaccination with aQIV were similar to those after primary vaccination.1
In Study-1, 607 subjects from the first season of the parent study in the US and Finland were revaccinated with the same vaccine as the prior year (aQIV/aQIV or trivalent non-adjuvanted influenza vaccine (TIV)/ quadrivalent non-adjuvanted influenza vaccine (QIV)). The results demonstrated that revaccination with aQIV induced a higher immune response against all 4 homologous strains, as well as heterologous strains, compared with those who received non-adjuvanted vaccines.1
In Study-2, 1601 subjects from the second season of the parent study in Finland, Thailand, and the Philippines were randomized to be revaccinated with either the same or the alternative vaccine as the prior year (aQIV/aQIV; aQIV/QIV; QIV/aQIV; QIV/QIV). The results showed a superior immune response for the aQIV/aQIV group versus aQIV/QIV group in 3 out of 4 homologous strains (A/H1N1 and both B strains). Also, subjects that were previously vaccinated with either aQIV or QIV demonstrated a more robust immune response with aQIV versus QIV for 3 of 4 strains. Revaccination with aQIV also demonstrated a higher persistence (at day 181 post-vaccination) for 2 out of the 4 strains and a broader immune response against heterologous strains as compared with non-adjuvanted vaccine.1
Another clinical trial was conducted during influenza seasons (2013/14, 2014/15) where the prevalent circulating viruses were antigenically different than the vaccine strain (vaccine-heterologous strains). The study was conducted in two study populations: subjects aged 6-23 months with no history of vaccination or pre-existing antibody titers and subjects aged 36-71 months with known history of influenza vaccination and high levels of pre-existing antibody titers. The objective of the study was to test if adjuvant activity was higher in subjects with lower pre-existing immunity, therefore yielding relative higher efficacy. The results showed that adjuvanted vaccines improved the cross-reactive antibody response in subjects with lower pre-existing antibody titers, regardless of their age or vaccine history.2
MF59®-Adjuvanted Pandemic Influenza Vaccine in the Pediatric, Adult, & Elderly Populations
The risk of influenza-associated morbidity and mortality is potentially higher with pandemic influenza than with seasonal influenza because of the lack of existing immunity to the virus in the general human population.20 Broad heterologous antibody response was assessed in pediatric, adult and elderly populations following vaccination with an MF59® adjuvanted pandemic vaccine.3,4
In the pediatric Phase II study (V89_11), a total of 322 subjects aged 6 months through 17 years received full doses of a MF59® adjuvanted, cell-derived influenza A (H5N1) vaccine (aH5N1c) three weeks apart.4 In two separate but similar adult and elderly Phase II studies (V89_13; V89_04), a total of 975 subjects aged 18 to 64 years of age and 1,388 subjects 65 years of age and older were equally randomized to received two full or half doses of a MF59® adjuvanted, cell-derived influenza A (H5N1) vaccine (aH5N1c) three weeks apart.3 A full-dose was 7.5 μg HA of H5N1 with 0.25 mL MF59® for a total injection volume of 0.5 mL, and a half-dose was 3.75 μg HA of H5N1 with 0.125 mL MF59® for a total injection volume of 0.25 mL.3,4,14
Antibody responses against five pre-determined H5N1 clades were measured by hemagglutination inhibition (HI) and microneutralization (MN) assays in pre-defined exploratory analyses. Adult and elderly subjects that received the full dose demonstrated increased immunogenicity against heterologous A (H5N1) strains from five different clades.3 Pediatric subjects that received the full dose demonstrated increased immunogenicity against heterologous A (H5N1) strains.4
About Pandemic Influenza
Pandemic influenza, as with seasonal influenza, is a contagious airborne respiratory disease which is unpredictable and can occur in any age group or any population worldwide. The risk of influenza-associated morbidity and mortality is greater with pandemic influenza than with seasonal influenza because of little or no pre-existing immunity to the virus in the human population. Four influenza pandemics have occurred over the past century, with the 1918 pandemic being the most severe in recent history, estimated to have killed up to 50 million people worldwide.21
