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Seqirus Presents New Clinical Data that Reinforce the Ability of MF59® Adjuvanted Seasonal and Pandemic Influenza Vaccines to Increase Immune Response

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.


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

About Seasonal Influenza

Influenza is a common, highly contagious infectious disease that can cause severe illness and life-threatening complications in many people.22 To reduce the risk of more serious outcomes, such as hospitalization and death, resulting from influenza, the CDC recommends annual vaccination for all individuals aged 6 months and older.23 Because transmission to others may occur one day before symptoms develop and up to 5 to 7 days after becoming sick, the disease can be easily transmitted to others. Influenza can lead to clinical symptoms varying from mild to moderate respiratory illness to severe complications, hospitalization and in some cases death.22 The CDC estimates that 959,000 people in the United States were hospitalized due to influenza-related complications during the 2017-2018 influenza season.24 Since it takes about 2 weeks after vaccination for antibodies to develop in the body that protect against influenza virus infection, it is best that people get vaccinated to help protect them before influenza begins spreading in their community.23

About the Influenza A (H5N1) Vaccine

Influenza A (H5N1) Monovalent Vaccine, Adjuvanted is a pandemic influenza vaccine developed by Seqirus. This is the first and only adjuvanted, cell-based pandemic vaccine to provide active immunization against the influenza A virus H5N1 strain. Seqirus has combined two technologies—MF59® adjuvant and cell-based antigen manufacturing—to create this first-of-its-kind pandemic influenza vaccine.

About Seqirus

Seqirus is part of CSL Limited (ASX:CSL), headquartered in Melbourne, Australia. The CSL Group of companies employs more than 22,000 people with operations in more than 60 countries.

Seqirus was established on 31 July 2015 following CSL’s acquisition of the Novartis influenza vaccines business and its subsequent integration with bioCSL. As one of the largest influenza vaccine providers in the world, Seqirus is a major contributor to the prevention of influenza globally and a transcontinental partner in pandemic preparedness. Seqirus operates state-of-the-art production facilities in the U.S., the UK and Australia, and manufactures influenza vaccines using both egg-based and cell-based technologies. It has leading R&D capabilities, a broad portfolio of differentiated products and a commercial presence in more than 20 countries.

About CSL

CSL (ASX:CSL) is a leading global biotechnology company with a dynamic portfolio of life-saving medicines, including those that treat haemophilia and immune deficiencies, as well as vaccines to prevent influenza. Since our start in 1916, we have been driven by our promise to save lives using the latest technologies. Today, CSL — including our two businesses, CSL Behring and Seqirus - provides life-saving products to more than 60 countries and employs more than 22,000 people. Our unique combination of commercial strength, R&D focus and operational excellence enables us to identify, develop and deliver innovations so our patients can live life to the fullest. For more information about CSL Limited, visit

For more information visit and

MF59® is a registered trademark of Novartis International AG, Basel, Switzerland.

Intended Audience 
This press release is issued from Seqirus USA Inc. in Summit New Jersey, USA and is intended to provide information about our global business. Please be aware that information relating to the approval status and labels of approved Seqirus products may vary from country to country. Please consult your local regulatory authority on the approval status of Seqirus products.

Forward-Looking Statements 
This press release may contain forward-looking statements, including statements regarding future results, performance or achievements. These statements involve known and unknown risks, uncertainties and other factors which may cause our actual results, performance or achievements to be materially different from any future results, performances or achievements expressed or implied by the forward-looking statements. These statements reflect our current views with respect to future events and are based on assumptions and subject to risks and uncertainties. Given these uncertainties, you should not place undue reliance on these forward-looking statements.




Polina Miklush 
+1 (908) 608-7170


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