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New Data Supports the Effectiveness of Adjuvanted Seasonal Influenza Vaccine in Reducing Influenza-Related Hospitalizations and Healthcare Costs in Older Adults


Seqirus, a global leader in influenza prevention and a business of CSL Limited (ASX:CSL), today announced new real-world evidence (RWE) supporting the relative effectiveness of FLUAD® (Influenza Vaccine, Adjuvanted), its adjuvanted trivalent vaccine (aTIV), compared with standard-dose, non-adjuvanted trivalent influenza vaccine (TIV) and standard-dose quadrivalent influenza vaccine (QIV) in reducing influenza-related outcomes over 18 influenza seasons in Italy.1 Additionally, two studies demonstrated the cost effectiveness of FLUAD® QUADRIVALENT (Influenza Vaccine, Adjuvanted), its adjuvanted quadrivalent seasonal influenza vaccine (aQIV) in Spain and France.2,3 These data were presented at the European Scientific Working Group on Influenza (ESWI) 8th Virtual Conference held from December 4-7, 2021.  

An adjuvant, such as MF59®, is designed to help boost the immune response to influenza vaccination in adults aged 65 years and older, who are more susceptible to flu complications.4 Adjuvanted influenza vaccines are authorized for use in many national immunization programs around the world to help protect people against influenza.

“Age-related immune decline can make it harder for the body to mount a sufficient immune response to flu vaccination in people aged 65 and older, who currently account for an estimated 727 million people globally – a number expected to double by 2050,” said Gregg Sylvester, MD, Chief Medical Officer, Seqirus.5 “The data presented at ESWI 2021 provide new evidence for the adjuvanted influenza vaccines in this population.” 

New data from an independent study highlighted the relative effectiveness of aTIV compared with TIV and QIV against all-cause or respiratory-related hospitalization in adults aged 65 and older across 18 consecutive influenza seasons in Italy (2001/02 to 2018/19).1 In this study, findings demonstrated that aTIV was associated with 12% lower risk of hospitalization and a 37% lower risk of respiratory-related hospitalizations compared with TIV and QIV.1

A separate study presented at the conference utilized a decision tree model, which was calibrated to estimate influenza-related costs and benefits of aQIV and high-dose quadrivalent influenza vaccine (QIV-HD) in a one-year time span.2 Results suggest that the use of aQIV may lead to an increase in quality-adjusted life years and substantial cost savings in Spain.2

“In Spain alone, nearly one fifth of the population is aged 65 and older as of 2020, and this percentage can be expected to grow in the coming years,” said Sergio Marquez-Pelaez, Pablo de Olavide University, Seville, and study-co-author.6 “The use of enhanced seasonal influenza vaccines, such as those that utilize an adjuvant, not only help to reduce influenza-related outpatient visits and hospitalizations in this population but may also reduce the economic and societal burden associated with increased outpatient medical encounters, as suggested by the data presented at ESWI.”2

Researchers also presented a budget impact model analysis in France that concluded utilizing aQIV in place of QIVe over a three year period may result in increased vaccination costs of about €90.7M, but could yield potential savings totaling €66.3M from fewer influenza events and complications driven by avoidance of medical care visit costs, outpatient complication costs and inpatient complication costs.3 These findings are similar to the published models in the UK and Italy, evaluating cost effectiveness of adjuvanted quadrivalent influenza vaccine.7,8 

The World Health Organization (WHO) estimates that seasonal influenza may result in nearly 290,000 to 650,000 respiratory deaths each year.9 The WHO recommends annual vaccination as the most effective way to prevent influenza, especially for people at a higher risk of influenza complications such as individuals over 65 years of age.10 

Effectiveness of adjuvanted trivalent vaccine (aTIV) for influenza over 18 epidemic seasons
The relative effectiveness of aTIV compared to TIV/QIV against all-cause hospitalization or respiratory-related hospitalization in older adults (≥65 years) was determined in an independent study across 18 consecutive influenza seasons in Italy.1 A nested case-control analysis of older adults was conducted using an Italian data source of primary care called the Health Search Database.1 Conditional logistic regression was used to estimate outcomes in a cohort of 58,252 older adults vaccinated with aTIV or TIV/QIV.1

The use of aTIV was associated with a 12% lower risk of hospitalization (OR=0.88; 95% CI: 0.80-0.98) and a 37% lower risk of respiratory-related hospitalizations (OR=0.63; 95% CI: 0.44-0.91) compared to TIV/QIV across 18 influenza seasons in Italy.1

The study was subject to the typical limitations associated with retrospective cohort analyses. Observational studies have limitations including the potential for selection bias and residual confounding. Individual study limitations may include: retrospective analyses, a potential lack of laboratory confirmed influenza, and varying data sources.

An Economic Evaluation of Enhanced Influenza Vaccines for the Elderly in Spain. The Adjuvanted Quadrivalent Influenza Vaccine versus High-Dose Quadrivalent Influenza Vaccine
The authors evaluated the cost-effectiveness of aQIV compared with QIV-HD in older adults aged 65 and above in Spain using a decision-tree model with Spanish demography and costs extracted from Spanish and European published literature as well as Spanish tender prices for aQIV and QIV-HD.2

Results suggest that vaccination with aQIV in older adults helped prevent 4,141 symptomatic influenza cases, 759 office visits, 441 hospitalizations, and 25 deaths annually, resulting in an increase of 211 quality-adjusted life years and substantial cost savings compared with QIV-HD.2 From payer and societal perspectives, about €63M and €64M savings, respectively, were estimated in the model.2

Budget Impact Analysis of the MF59-Adjuvanted Quadrivalent Influenza Vaccine in the Older Adult French Population
Seqirus also presented an evaluation of the budget impact of a national immunization program in France based on the progressive use of aQIV instead of standard egg-based QIV (QIVe) or QIV-HD.3 The model forecasts influenza-related costs and benefits for the next 3 seasons, starting in 2021.3

Over a 3-year period, it was estimated that 56,028 influenza cases, 13,449 medical care visits, 30,815 outpatient complications, 3,902 inpatient complications, and 745 influenza-associated deaths may be prevented by switching from QIVe to aQIV vaccinations.3 Results suggest that progressively transitioning from QIVe to aQIV could potentially result in increased vaccination costs of about €90.7M, with about €66.3M in savings from fewer influenza events and complications, driven by avoidance of medical care visit costs (€470K), outpatient complication costs (€788K), and inpatient complication costs (€23.2M).3 

Economic evaluations in health can be a very useful complement to the decision-making process, and the methodological approaches should be continually refined and improved. Caution must be exercised in interpreting the results of economic evaluations performed in a given setting and in extrapolating to a different population, location, healthcare systems and resource use. It’s strongly suggested that economic evaluations should be performed on a regular basis to ensure that the results are valid and up-to-date, and consistent with payer’s views and priorities of the societies which are under research.

About Seasonal Influenza
Influenza is a common, contagious seasonal respiratory disease that may cause severe illness and life- threatening complications in some people.11 Influenza can lead to clinical symptoms varying from mild to moderate respiratory illness to severe complications, hospitalization and in some cases, death.11 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.11 Estimates from the CDC report that during the 2019/20 influenza season, there were an estimated 380,000 influenza-related hospitalizations in the U.S.12 The CDC recommends annual vaccination for individuals aged 6 months and older, who do not have any contraindications.13  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.13 The CDC recommends that people get vaccinated by the end of October.13 

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; USOTC:CSLLY) is a leading global biotechnology company with a dynamic portfolio of lifesaving 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 lifesaving products to patients in more than 100 countries and employs more than 25,000 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 inspiring stories about the promise of biotechnology, visit and follow us on

For more information about CSL Limited, visit

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.


FLUAD® (Influenza Vaccine, Adjuvanted) and FLUAD® QUADRIVALENT (Influenza Vaccine, Adjuvanted)


FLUAD and FLUAD QUADRIVALENT are vaccines that helps protect against the flu. FLUAD and FLUAD QUADRIVALENT are for people age 65 years and older. 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 shot. 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 shot was given
  • Muscle aches
  • Headache
  • Tiredness

These are not all of the possible side effects of FLUAD and FLUAD QUADRIVALENT. You can ask your healthcare provider for a complete list of possible side effects.

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 at 1- 855-358-8966 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 vaccine, please see the full Prescribing Information for FLUAD or FLUAD QUADRIVALENT. The information provided here is not comprehensive. To learn more, talk about FLUAD and/or FLUAD QUADRIVALENT with your healthcare provider or pharmacist.

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


Jon Steed
+1 (908) 517-6379


Lapi, F., Rossi, A., Sessa, A., et. al. (2021). Effectiveness of adjuvanted trivalent vaccine (aTIV) for influenza over 18 epidemic seasons. Presented at ESWI 2021 (December 4-7, 2021).  

Marquez Pelaez, S., Gani, R., Alvarez, P., et. al. (2021). An Economic Evaluation of Enhanced Influenza vaccines for the Elderly in Spain. The Adjuvanted Quadrivalent Influenza Vaccine versus High-Dose Quadrivalent Influenza Vaccine. Presented at ESWI 2021 (December 4-7, 2021).  

Nguyen, V., D’Agostino, P., McCracken, A., et. al. (2021). Budget Impact Analysis of the MF59-Adjuvanted Quadrivalent Influenza Vaccine in the Older Adult French Population. Presented at ESWI 2021 (December 4-7, 2021). 

Centers for Disease Control and Prevention (CDC). (2021). Adjuvanted Flu Vaccines. Retrieved from: Accessed November 2021.

United Nations. (2020). World Population Ageing 2020 Highlights. Retrieved from: Accessed November 2021.

National Institute of Statistics (INE). (2021). Resident population by date, sex and age. Retrieved from: Accessed November 2021. 

Italian Journal of Public Health. (2021). Valutazione di Health Technology Assessment (HTA) del vaccino antinfluenzale quadrivalente adiuvato: Fluad Tetra. Accessed November 2021.

Human Vaccines & Immunotherapeutics. (2021). The cost-effectiveness of an adjuvanted quadrivalent influenza vaccine in the United Kingdom. Retrieved from: Accessed November 2021.

The World Health Organization (WHO). Global Influenza Programme. Retrieved from: Accessed November 2021.

10 WHO. (2018). Influenza (Seasonal). Retrieved from: Accessed November 2021.

11 CDC. (2019). Key Facts about Influenza (Flu). Retrieved from: Accessed November 2021.

12 CDC. (2020). Estimated Influenza Illnesses, Medical visits, Hospitalizations, and Deaths in the United States — 2019–2020 Influenza Season. Retrieved from: Accessed November 2021.

13 CDC. (2021). Who Needs a Flu Vaccine and When. Retrieved from: Accessed November 2021.