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Seqirus Presents New Real-World Evidence on Relative Effectiveness of Adjuvanted Seasonal Influenza Vaccine in Adults 65 Years and Older at IDWeek 2020


Seqirus, a global leader in influenza prevention, today presented new real-world evidence (RWE) on the effectiveness of an MF59® adjuvanted, trivalent seasonal influenza vaccine (aTIV) in adults 65 years and older during the 2018/19 U.S. influenza season at the IDWeek 2020 virtual conference.1

aTIV was found to be more effective than a high-dose trivalent influenza vaccine (TIV-HD) in seven out of eleven outcomes assessed, including reducing influenza-related medical office visits and cardio-respiratory disease (CRD)-related hospitalizations/emergency room (ER) visits in adults 65 years and older during the 2018/19 U.S. influenza season.[1] The study also found that the relative influenza vaccine effectiveness (rVE) of aTIV was comparable to TIV-HD against influenza-related hospitalizations/ER visits and all-cause hospitalization/ER visits.1 In an economic analysis, aTIV was also statistically comparable to TIV-HD.1

The vaccines examined in this study are the only influenza vaccines specifically indicated for adults 65 years and older in the U.S.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]

“This study underscores the important role an adjuvanted influenza vaccine can play in improving influenza-related outcomes in older adults. These data are consistent with a recent publication in Vaccines that showed aTIV was more effective than a standard-dose, non-adjuvanted trivalent seasonal vaccine in reducing influenza-related office visits and hospitalizations during the 2017/18 U.S. influenza season,” said Stephen I. Pelton, MD, Professor of Pediatrics at Boston University School of Medicine, former Chief of Pediatrics Infectious Diseases at Boston Medical Center, and study author.[8] “The data presented at IDWeek indicates that an MF59®-adjuvanted influenza vaccine is a valuable tool to help improve influenza-related outcomes in adults 65 years and older, an age group associated with a significantly higher risk of complications from seasonal influenza.”

This retrospective cohort analysis was conducted using data from several databases: professional fee claims, prescription claims and hospital charge master data in the U.S.1 In addition to the clinical outcome measures the study also evaluated all-cause and influenza-related healthcare resource utilization (HCRU) and annualized costs.1 Both aTIV and TIV-HD were comparable in terms of predicted mean annualized costs for influenza-related office visits and influenza-related hospitalizations. Annualized all-cause and influenza-related total costs per patient were also comparable between aTIV and TIV-HD.1

“Particularly for adults 65 years and older, the importance of influenza vaccination 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 healthcare resources,” said Gregg Sylvester, MD, Chief Medical Officer at Seqirus.[9] “RWE studies like the one presented at IDWeek provide insight into how our influenza vaccines operate in real-world settings, serving as a tool to help optimize our vaccine strategies. As part of our leading role on the front line of influenza prevention, Seqirus is proud to offer an adjuvanted seasonal influenza vaccine that is specifically designed to help protect older adults that are at increased risk of influenza-related complications.”

This MF59® adjuvanted influenza vaccine has an extensive clinical legacy, with 155+ million doses distributed over 20+ years* and licensure in 30 countries.[10]  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 is available for the 2020/21 influenza season.[11]

*Doses distributed globally as of September 2020, including both trivalent and quadrivalent formulations.10

About the Study

The primary objective of the study was to evaluate the relative vaccine effectiveness (rVE) against influenza-related hospitalizations/ER visits, influenza-related office visits and cardio-respiratory disease (CRD)-related hospitalizations/ER visits and compare all-cause and influenza-related costs associated with two vaccines specifically designed for older adults (≥ 65 years), adjuvanted trivalent influenza vaccine (aTIV) and high-dose trivalent influenza vaccine (TIV-HD) for the 2018/19 influenza season.1

A retrospective analysis was conducted using U.S. claims and hospital data.1 For clinical evaluations, adjusted analyses were conducted following inverse probability of treatment weighting (IPTW) to control for selection bias.1 Poisson regression was used to estimate the adjusted rVE against influenza-related hospitalizations/ER visits, influenza-related office visits, and any CRD-related hospitalizations/ER visits.1 Adjusted rVE analysis indicated that aTIV was more effective than TIV-HD in reducing influenza-related office visits (rVE=6.6%; 95% CI: 2.8%-10.3%) and CRD-related hospitalizations/ER visits (rVE=2.6%; 95% CI: 2.0%-3.2%) in adults 65 years and older during the 2018/19 U.S. influenza season.1 aTIV was found to be statistically comparable to TIV-HD through adjusted rVE analysis in preventing influenza-related hospitalizations/ER visits (rVE=2.0%; 95% CI: -3.7%-7.3%) and all-cause hospitalizations (rVE=0.63%; 95%CI: -0.09%-1.3%).1 No treatment effect was observed between the aTIV and TIV-HD groups for UTI hospitalizations (control condition) (rVE=0.97%; 95% CI: -1.6%-3.5%).1

Influenza-related hospitalizations/ER visits were defined as a hospitalization or ER visit with a diagnosis code for influenza.1 Influenza-related office visits were defined as a physician office visit in diagnosis (Dx) or outpatient charge description master (CDM) with a diagnosis code for influenza in any position.1 CRD-related outcomes were defined as a hospitalization or ER visit with a diagnosis code in any position for the cardio-respiratory event of interest.1

Additionally, an economic evaluation was conducted to compare influenza-related healthcare resource utilization (HCRU) and annualized costs between patients that received aTIV and TIV-HD.1 The analysis found that predicted mean annualized all-cause and influenza-related total costs were statistically comparable between aTIV and TIV-HD (US$9,676 vs US$9,625 and US$18.74 vs US$17.28, respectively; all p>0.05).1 Furthermore, aTIV and TIV-HD were comparable in predicted mean annualized costs for influenza-related office visits (US$1.29 vs US$1.34; p=0.334), influenza-related hospitalization (US$20.28 vs US$18.13; p=0.128), and influenza-related ER visits (US$2.18 vs US$2.32; p=0.220).1

These findings are consistent with a previous Seqirus-sponsored study conducted during the 2017-18 influenza season using similar methodologies, recently published in Vaccines.8

This study was subject to the typical limitations associated with retrospective analysis studies.1 Though the cohorts were matched using standard techniques, there could be other variables not included in the study that could have skewed the balance of the groups.1 Additionally, there are limitations related to the utilization of claims data; for example, socioeconomic characteristics such as race/ethnicity, income, and access to care were not available.1 Finally, the claims database did not provide the clinical data to confirm influenza through lab or test results.1

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 Centers for Disease Control and Prevention (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

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) and FLUAD® QUADRIVALENT (Influenza Vaccine, Adjuvanted)



What is FLUAD® (Influenza Vaccine, Adjuvanted) and FLUAD® QUADRIVALENT (Influenza Vaccine, Adjuvanted)?

FLUAD and FLUAD QUADRIVALENT are vaccines that help protect people aged 65 years and older from the flu. Vaccination with FLUAD or FLUAD QUADRIVALENT may not protect all people who receive the vaccine.

Who should not get FLUAD or FLUAD QUADRIVALENT?

You should not get FLUAD or FLUAD QUADRIVALENT 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 allergic reaction to a previous influenza vaccine.

Before receiving FLUAD or FLUAD QUADRIVALENT, 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 or FLUAD QUADRIVALENT 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 and FLUAD QUADRIVALENT?

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

These are not all of the possible side effects of FLUAD or FLUAD QUADRIVALENT. 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 or FLUAD QUADRIVALENT.

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

FLUAD® and FLUAD® QUADRIVALENT are registered trademarks of Seqirus UK Limited or its affiliates.

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






Polina Miklush
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[1] Pelton, S.I., Divino, V., Postma, M.J., et al. (2020). MF59 ASSURANCE 2: A Real-world Study to Estimate the Relative Vaccine Effectiveness of Adjuvanted Trivalent Influenza Vaccine Compared to Egg-based Trivalent High-dose Among U.S. Older Adults During 2018-19 Influenza Season. Presented at IDWeek 2020 virtual conference.

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

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

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

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

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

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

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

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