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Seqirus Publishes New Real-World Evidence (RWE) on Relative Effectiveness of Adjuvanted Seasonal Influenza Vaccine in Adults 65 Years and Older in Vaccines

This news release is intended for business and trade media only.


Summit, NJ

Seqirus, a global leader in influenza prevention, today announced the publication of new real-world evidence (RWE) that demonstrated an MF59® adjuvanted, trivalent influenza vaccine (aTIV) was more effective than a standard-dose non-adjuvanted trivalent seasonal vaccine in preventing influenza-related medical office visits and hospitalizations in adults 65 years and older during the 2017/18 U.S. influenza season.[1] The study assessed relative influenza vaccine effectiveness (rVE) of aTIV compared to non-adjuvanted seasonal influenza vaccines including high-dose trivalent vaccine, standard-dose quadrivalent vaccine and standard-dose trivalent vaccine.1 The study also demonstrated that the effectiveness of aTIV and a high-dose trivalent influenza vaccine was comparable in the same population during the study season, emphasizing the critical role enhanced vaccines play in protecting adults 65 years and older against influenza.1

This is the first Seqirus-sponsored study to conduct an economic burden analysis using a claims dataset comparing aTIV and a high-dose trivalent influenza vaccine. The data revealed the all-cause and total influenza-related healthcare costs were comparable among older adults vaccinated with aTIV or a high-dose trivalent influenza vaccine during the 2017/18 influenza season.1 The vaccines included in the economic burden analysis are the only influenza vaccines specifically indicated for patients 65 years and older. Costs included those associated with all-cause total healthcare costs, influenza-related hospitalization costs, influenza-related ER costs, influenza-related office visits and antiviral treatment costs, and influenza-related total costs.1

In the U.S., influenza causes significant morbidity and mortality in adults 65 years and older, as demonstrated by higher hospitalization and death rates in most influenza seasons.[2] Age-related immune decline in this population can also result in a lower immune response to standard influenza vaccines, which may impact vaccine effectiveness.[3],[4] Adding MF59® adjuvant to an influenza vaccine is designed to enhance the immune response to the influenza strains contained in the vaccine in adults 65 years and older.[5],[6],[7]

“Adults 65 years and older are at a significantly higher risk of complications from seasonal influenza, including pneumonia, and bronchitis, as well as heart attack, compared with young, healthy adults,” said Stephen I. Pelton, MD, Professor of Pediatrics at Boston University School of Medicine and former Director of Pediatrics Infectious Diseases at Boston Medical Center and study author.2,[8],[9] “The Centers for Disease Control (CDC) estimates that between 50 and 70 percent of seasonal influenza-related hospitalizations occurred in U.S. adults 65 and older*.2 Our data, published in Vaccines, demonstrate the important role enhanced vaccines contribute to prevention of influenza in vulnerable populations and their potential to help reduce influenza-related morbidity and treatment costs.”

This study evaluated the relative vaccine effectiveness (rVE) of aTIV compared with non-adjuvanted seasonal influenza vaccines including high-dose trivalent vaccine, standard-dose quadrivalent vaccine and standard-dose trivalent vaccine in adults 65 years and older, during the 2017-2018 U.S. influenza season. This retrospective cohort analysis used de-identified data from databases, including prescription claims, professional fee claims and hospital charge master data.1 Individuals who received aTIV had a significantly lower rate of influenza-related medical office visits and influenza-related hospitalization/ER visits, compared to those who received standard-dose, non-adjuvanted vaccines.1 When compared with high-dose trivalent influenza vaccine, the effectiveness of aTIV was comparable in reducing the rate of influenza-related hospitalizations/ER visits.1

“The importance of influenza vaccination, particularly for adults 65 years and older, is evident now more than ever amidst the ongoing COVID-19 pandemic, as it can help to not only reduce the impact of influenza, but also minimize the additional burden on health care infrastructure,”[10] said Gregg Sylvester, MD, Chief Medical Officer at Seqirus. “As part of our role on the front line of influenza prevention, we are always looking for new ways to innovate and address the challenges to help protect against influenza and its potentially serious complications in adults 65 years of age and older. These new data underscore the importance of RWE to understand how our influenza vaccines work in real world settings.”

This MF59® adjuvanted trivalent influenza vaccine has an extensive clinical legacy, with 144+ million doses distributed and licensure in 30 countries since it was first approved in 1997.[11]

About the Study

The primary objective of the study was to assess the relative vaccine effectiveness (rVE) of adjuvanted trivalent influenza vaccine (aTIV) compared with other non-adjuvanted, standard and high dose seasonal influenza vaccines, and to compare influenza-related healthcare resource use (HCRU) and costs between patients that received aTIV and high-dose trivalent influenza vaccine (TIV-HD).1

Using data from IQVIA’s Integrated Data Warehouse, which include Professional Fee Claims (Dx), Prescription Claims (Rx) and Hospital Charge Data Master (CDM), researchers studied adults 65 years and older who were vaccinated with aTIV, TIV-HD, non-adjuvanted, quadrivalent standard dose influenza vaccine (QIV-SD), and non-adjuvanted, trivalent standard dose influenza vaccine (TIV-SD) during the 2017/18 U.S. influenza season. Adjusted rVE analysis indicated that aTIV was significantly more effective in preventing influenza-related medical office visits and influenza-related hospitalization/ER visits compared to QIV-SD and TIV-SD, and comparably effective to TIV-HD.1 Additionally, participants who received aTIV had significantly lower rates of all-cause hospitalizations and pneumonia and asthma/COPD/bronchial hospitalizations, compared with TIV-SD.1                            

Influenza-related medical office visits were defined in the study based on a physician office visit with a claim for a rapid influenza diagnostic test followed by antiviral treatment within two days of the test, and influenza-related hospitalization/ER visits were defined as patients with a diagnosis code for influenza.1

Additionally, an economic analysis was conducted to compare influenza-related healthcare resource use (HCRU) and costs between patients that received aTIV and TIV-HD. These two vaccines were included in the analysis as they are the only influenza vaccines with specific indications for patients 65 years and older. The analysis found that all-cause and influenza-related total costs were comparable between aTIV and TIV-HD.1

This study was subject to the typical limitations associated with retrospective database studies. A potential limitation of this study is the study estimates were obtained from a sample of adults using linked claims and hospital data.1 Additionally, the presence of influenza could not be confirmed using laboratory test results due to the absence of this clinical detail in the utilized databases.1

*Recent years include 2010/11 to 2018/19 influenza seasons.

About Seasonal Influenza 

Influenza is a common, contagious seasonal respiratory disease that may cause severe illness and life-threatening complications in some people.[12] Influenza can lead to clinical symptoms varying from mild to moderate respiratory illness to severe complications, hospitalization and in some cases, death.12 The CDC recommends annual vaccination for individuals aged 6 months and older, who do not have any contraindications.[13]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.12 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.[14] 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.12 The CDC recommends that people get vaccinated by the end of October.[15] 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.15 Vaccines are typically available until January or as long as influenza viruses are circulating to ensure as many people are vaccinated as possible prior to the start of the influenza season.

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 70 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 U.S. Inc. in Summit New Jersey, U.S. 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.


FLUAD® (Influenza Vaccine, Adjuvanted)



What is FLUAD® (Influenza Vaccine, Adjuvanted)?

FLUAD is a vaccine that helps protect people aged 65 years and older from the flu. Vaccination with FLUAD may not protect all people who receive the vaccine.

Who should not get FLUAD?

You should not get FLUAD if you have had a severe allergic reaction to any of the ingredients in the vaccine in the past, including egg protein, or a severe reaction to a previous influenza vaccine.

Before receiving FLUAD, tell your healthcare provider about all medical conditions, including if you:

  • have ever had Guillain-Barré syndrome (severe muscle weakness) within six weeks after getting a flu vaccine. The decision to give FLUAD should be made by your healthcare provider, based on careful consideration of the potential benefits and risks.
  • have problems with your immune system or are taking certain medications that suppress your immune system, as these may reduce your immune response to the vaccine
  • have ever fainted when receiving a vaccine

What are the most common side effects of FLUAD?

  • Pain or tenderness where the vaccine was given
  • Muscle aches
  • Headache
  • Fatigue


These are not all of the possible side effects of FLUAD. You can ask your healthcare provider for more information.

What do I do if I have side effects?

Ask your healthcare provider for advice about any side effects that concern you.

To report SUSPECTED ADVERSE REACTIONS, contact Seqirus USA Inc. at 1‐844‐275‐ 2461 or VAERS at 1‐800‐822‐7967 or

You are also encouraged to report negative side effects of prescription drugs to the FDA. Visit, or call 1‐800‐FDA‐1088.


Before receiving this vaccine, please see the full US Prescribing Information for FLUAD.

The information provided here does not include all that is known about FLUAD. To learn more, talk about FLUAD with your healthcare provider.


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

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





Polina Miklush
+1 (908)


[1] Pelton, S.I., Divino, V., Postma, M.J., et al. (2020). A real-world study evaluating the relative vaccine effectiveness of adjuvanted trivalent influenza vaccine compared to high-dose trivalent and other egg-based influenza vaccines among older adults in the US during the 2017-18 influenza season. Vaccine.

[2] Centers for Disease Control and Prevention (CDC). (2019). People 65 years and older & influenza. Retrieved from: Accessed August 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] Rothberg MB, Haessler SD, Brown RB. (2008). Complications of viral influenza. Am J Med. 2008;121(4):258-264.

[9] National Foundation for Infectious Diseases. (NFID). (2016). Call to action: Reinvigorating influenza prevention in US adults age 65 and older. Retrieved from: Accessed August 2020.

[10] CDC. (2020). Frequently Asked Influenza (Flu) Questions: 2020 – 2021 Season. Retrieved from: Accessed August 2020.

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

[12] CDC. (2019). Key facts about influenza (flu). Retrieved from: Accessed August 2020.


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

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


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