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Seqirus Presents New Late-Breaking Data at ESWI 2020 Highlighting Benefits of MF59®-Adjuvanted Seasonal Influenza Vaccine


Seqirus, a global leader in influenza prevention and influenza pandemic response, today announced new late-breaking data from a systematic review and meta-analysis presented at the European Scientific Working Group on Influenza (ESWI) virtual conference confirming the benefit of an MF59®-adjuvanted trivalent seasonal influenza vaccine (aTIV) for adults 65 years and older.[1] Results indicate that relative vaccine effectiveness (rVE) favored aTIV over non-adjuvanted standard dose quadrivalent and trivalent influenza vaccines in averting influenza-related medical encounters.1 aTIV was comparable to a high-dose TIV for the same outcome.1

Influenza causes significant morbidity and mortality in adults 65 years and older, as demonstrated by higher hospitalization and death rates in most recent years, compared with young, healthy adults.[2] Seasonal influenza vaccine effectiveness may be impacted by age-related immune decline in this population, which can result in reduced immune response to standard influenza vaccines.[3],[4] The MF59® adjuvant included in aTIV is designed to enhance the immune response to the influenza strains contained in the vaccine in adults 65 years and older.[5],[6],[7]

The data presented at ESWI 2020 comes from a systematic review and meta-analysis of 16 real-world studies over a period of 20 years that evaluated the effectiveness of vaccination with aTIV relative to non-adjuvanted egg-based influenza vaccines or no vaccine in adults 65 years or older.1

“To have results from a systematic review and meta-analysis provides an additional level of evidence for the benefit of adjuvanted influenza vaccines in older adults who face age-related immune decline,” said Brenda L. Coleman, RN, PhD, Infectious Disease Epidemiologist, Sinai Health System, Toronto; Assistant Professor, Dalla Lana School of Public Health, University of Toronto.

The MF59® adjuvant is designed to enhance the immune response by increasing the magnitude and persistence of antibody response and creating more diverse, cross-reactive antibodies.6,7,[8] This may be important when there is a mismatch between the virus strains included in the vaccine and the strains circulating in the community.7,[9],[10],[11],[12],[13]

“Adults age 65 years and older are at higher risk for complications from seasonal influenza. At Seqirus, we’re focused on utilizing advanced technology like the MF59® adjuvant to potentially offer better protection against influenza for those most vulnerable, like adults in this age group,” said Gregg Sylvester, MD, Chief Medical Officer at Seqirus. “With both COVID-19 and influenza circulating in the Northern Hemisphere this season, it’s critical that as many people as possible receive an influenza vaccine to protect against the flu, and therefore help to keep pressure off health systems during the continued pandemic.”

This MF59®-adjuvanted seasonal influenza vaccine has an extensive clinical legacy, with 155+ million doses distributed over 20+ years* and licensure in 30 countries.[14] The quadrivalent formulation of the MF59®-adjuvanted influenza vaccine, which adds an additional B strain to the trivalent formulation, was approved by the U.S. Food and Drug Administration (FDA) in February 2020 and in Europe in March 2020 and is available for the 2020/21 influenza season.[15]

*Doses distributed globally as of November 2020, including both trivalent and quadrivalent formulations.


About the Study

This abstract is a systematic review and meta-analysis on real-world studies that evaluated the effectiveness of vaccination with MF59®-adjuvanted trivalent seasonal influenza vaccine (aTIV) relative to vaccination with non-adjuvanted egg-based influenza vaccines or no vaccine in adults 65 years of age and above.1

The systematic review using Cochrane methods included 21 studies after screening 4,374 peer-reviewed journal articles published between January 1, 1997 and July 15, 2020.1 Of these 21 studies, 16 of these were considered sufficiently comparable to include in one of the meta-analyses.1 Pooled relative vaccine effectiveness (rVE) estimates are presented with their 95% confidence intervals.1

Meta-analysis of studies found that aTIV was effective in reducing general practice visits and hospital admissions (absolute VE).1 Pooled estimates of rVE favored aTIV over non-adjuvanted standard dose quadrivalent and trivalent influenza vaccines in averting influenza-related medical encounters.1 aTIV was comparable to high-dose TIV in averting influenza-related medical encounters.1 Although substantial heterogeneity was observed, estimates for rVE were consistently in favor of aTIV over the standard-dose non-adjuvanted vaccines, with the exception of one study.1


About Seasonal Influenza 

Influenza is a common, contagious seasonal respiratory disease that may cause severe illness and life-threatening complications in some people.[16] Influenza can lead to clinical symptoms varying from mild to moderate respiratory illness to severe complications, hospitalization and in some cases, death.16 The Centers for Disease Control and Prevention (CDC) recommends annual vaccination for individuals aged 6 months and older, who do not have any contraindications.[17] Because transmission of influenza viruses 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.16 Preliminary estimates from the CDC report that from October 1, 2019, through April 4, 2020, there were an estimated 410,000 to 740,000 influenza-related hospitalizations in the U.S.[18] Since it takes about two weeks after vaccination for antibodies to develop in the body that help protect against influenza virus infection, it is recommended that people get vaccinated before influenza begins spreading in their community.16 The CDC recommends that people get vaccinated by the end of October.[19] However, getting vaccinated too early (for example, in July or August), can be associated with reduced protection against influenza infection later in the flu season.19


About Seqirus

Seqirus is part of CSL Limited (ASX: CSL). 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. With state-of-the-art production facilities in the U.S., the U.K. and Australia, and leading R&D capabilities, Seqirus utilizes egg, cell and adjuvant technologies to offer a broad portfolio of differentiated influenza vaccines in more than 20 countries around the world.


About CSL

CSL (ASX:CSL) is a leading global biotechnology company with a dynamic portfolio of life-saving medicines, including those that treat hemophilia 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 100 countries and employs more than 27,000 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


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.


MF59® is a registered trademark of Seqirus UK Limited or its affiliates.



Polina Miklush
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[1] Effectiveness of the MF59-Adjuvanted Trivalent Seasonal Influenza Vaccine Among Adults Aged 65 or Older, a Systematic Review and Meta-analysis. Presented at ESWI.

[2] Centers for Disease Control and Prevention (CDC). (2019). People 65 years and Older & Influenza. Retrieved from: Accessed November 2020.

[3] Monto AS, Ansaldi F, Aspinall R, et al. (2009). Influenza control in the 21st century: Optimizing protection of older adults. Vaccine. 2009;27(37):5043-5053.

[4] McElhaney JE, Verschoor CP, Andrew MK, et al. (2020). The immune response to influenza in older humans: beyond immune senescence. BMC.

[5] Frey SE, Aplasca-De Los Reyes MR, Reynales H, et al. (2014). Comparison of the safety and immunogenicity of an MF59®-adjuvanted with a non-adjuvanted seasonal influenza vaccine in elderly subjects. Vaccine. 2014;32:5027-5034.

[6] O'Hagan DT, Ott GS, Nest GV, et al. (2013). The history of MF59® adjuvant: a phoenix that arose from the ashes. Expert Rev Vaccines. 2013;12(1):13-30.

[7] Banzhoff A, Pellegrini M, Del Giudice G, et al. (2008). MF59-adjuvanted vaccines for seasonal and pandemic influenza prophylaxis. Influenza Other Respir Viruses. 2008;2(6):243-24.

[8] O’Hagan DT, Ott GS, De Gregorio E, Seubert A. The mechanism of action of MF59—an innately attractive adjuvant formulation. Vaccine. 2012;30(29):4341-4348.

[9] Del Giudice G, Hilbert AK, Bugarini R, et al. An MF59-adjuvanted inactivated influenza vaccine containing A/Panama/1999 (H3N2) induced broader serological protection against heterovariant influenza virus strain A/Fujian/2002 than a subunit and a split influenza vaccine. Vaccine. 2006:24(16):3063-3065.

[10] Ansaldi F, Bacilieri S, Durando P, et al. Cross-protection by MF59™-adjuvanted influenza vaccine: neutralizing and haemagglutination-inhibiting antibody activity against A(H3N2) drifted influenza viruses. Vaccine. 2008;26(12):1525-1529.

[11] Ansaldi F, Zancolli M, Durando P, et al. Antibody response against heterogeneous circulating influenza virus strains elicited by MF59- and non-adjuvanted vaccines during seasons with good or partial matching between vaccine strain and clinical isolates. Vaccine. 2010;28(25):4123-4129.

[12] Frey SE, Reyes MR, Reynales H, et al. Comparison of the safety and immunogenicity of an MF59®-adjuvanted with a non-adjuvanted seasonal influenza vaccine in elderly subjects. Vaccine. 2014;32(39):5027-5034.

[13] Kavian N, Hachim A, Li APY, et al. Assessment of enhanced influenza vaccination finds that Fluad conveys an advantage in mice and older adults. Clin Transl Immunology. 2020;9(2):e1107.

[14] Data on file. Seqirus Inc; 2019.

[15] FLUAD® QUADRIVALENT (Influenza Vaccine, Adjuvanted) [package insert]. Holly Springs, NC: Seqirus Inc; 2020.

[16] CDC. (2019). Key Facts about Influenza (Flu). Retrieved from: Accessed November 2020.

[17] CDC. (2020). Key Facts About Seasonal Flu Vaccine. Retrieved from: Accessed November 2020.

[18] CDC. (2020). 2019-2020 U.S. Flu season: Preliminary burden estimates. Retrieved from: Accessed November 2020.

[19] CDC. (2020). Who Needs a Flu Vaccine and When. Retrieved from: Accessed November 2020.