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Seqirus Real World Evidence Published in Vaccine Highlights Value of Cell-Based Quadrivalent Influenza Vaccine in Preventing Influenza Related Hospitalizations in the U.S. 2017/18 Season

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 real-world evidence (RWE) on the company’s cell-based quadrivalent influenza vaccine (QIVc) in peer-reviewed medical journal Vaccine. Study results indicate QIVc was more effective compared with standard, egg-based quadrivalent vaccine (QIVe-SD) in preventing influenza-related hospitalizations/ER visits, all-cause hospitalizations, and hospitalizations/ER visits related to serious respiratory events.1 Study participants included commercially-insured U.S. subjects between 4 and 64 years of age during the 2017/18 influenza season. In a secondary economic analysis, the study also found that QIVc was associated with lower all-cause healthcare resource utilization (HCRU), a measurement of costs associated with hospitalizations, ER visits, and office visits, as well as all-cause costs, inclusive of outpatient hospital, pharmacy and medical expenses, compared with QIVe-SD.[1]

The RWE study is the first Seqirus-sponsored study to evaluate the effectiveness of QIVc in preventing influenza-related hospitalizations in adults under 65 years of age. Individuals ages 4 to 64 years old represent a significant population affected by seasonal influenza each year, underscoring the importance of annual vaccination in this age group.[2]

Real-world evidence is crucial in understanding seasonal influenza vaccine effectiveness, and this study adds to a growing body of evidence indicating that cell-based vaccines like QIVc may potentially result in better influenza-related outcomes compared to standard vaccine options in some seasons, particularly those characterized by egg-adapted changes,” said Maarten J. Postma, PhD, Professor of Global Health Economics at University of Groningen. “Vaccination against influenza is not only the best way to reduce the incidence of seasonal influenza, but also a critical tool to protect public health by minimizing the burden of influenza on our healthcare systems.”

The Centers for Disease Control and Prevention (CDC) recommends everyone six months and older without contraindications receive an annual influenza vaccine as the best way to prevent seasonal influenza.[3] Seasonal influenza vaccine effectiveness may vary each year; some of these factors may be due to the differences between the circulating influenza viruses and the World Health Organization (WHO)-selected strains contained in the vaccine.[4] This can occur if the circulating influenza virus strains mutate between the time of strain selection (recommendation by the WHO) and vaccine availability.[5] Change may also be introduced during the egg-based manufacturing process for influenza vaccines. The virus contained in the vaccine may undergo egg-adapted changes in order to successfully grow in eggs. This process can cause mutations, resulting in a vaccine virus that can be different from the intended, or circulating, vaccine strain.

“Amidst the ongoing COVID-19 pandemic, our commitment to being on the front line of influenza prevention is stronger than ever,” said Gregg Sylvester, MD, Chief Medical Officer at Seqirus. “RWE studies like this one are critical to provide ever-growing data and equip researchers, healthcare practitioners and policy makers with a complementary approach to measure the value of influenza vaccines. Practical insights on the year-over-year effectiveness of seasonal influenza vaccines from studies like these can help advance public health and support vaccine confidence.”

In the U.S., Seqirus operates a state-of-the-art cell-based manufacturing facility in Holly Springs, NC, purpose-built in partnership with the Biomedical Advanced Research and Development Authority (BARDA) to increase cell-based vaccine manufacturing capacity and combat pandemic influenza threats.[6] Cell-based influenza vaccine technology may offer advantages over the standard influenza manufacturing process including being more scalable and offering faster production in the event of an influenza pandemic.[7]

About the Study

This retrospective cohort analysis compared relative vaccine effectiveness (rVE) with cell-based quadrivalent influenza vaccine (QIVc) versus standard, egg-based quadrivalent vaccines (QIVe-SD) in commercially-insured U.S. subjects between 4 and 64 years of age during the 2017/18 influenza season.1

The study sample comprised 555,538 QIVc recipients and 2,528,524 QIVe-SD recipients. The study analyzed administrative claims data in the U.S. (IQVIA PharMetrics Plus® database). Subjects vaccinated with QIVc or QIVe-SD from August 1, 2017-January 31, 2018 were identified (date of vaccination termed the index date). Influenza-related hospitalizations/ER visits, all-cause hospitalizations and serious respiratory hospitalizations/ER visits were assessed post vaccination.1


Results indicate that, after adjustment, QIVc was more effective in preventing influenza-related hospitalizations/ER visits, all-cause hospitalizations, and hospitalizations/ER visits related to serious respiratory events compared with QIVe-SD. Similar trends were observed among subgroups of interest (4–17, 18–64 and 50–64 years, and subjects with ≥ 1 high-risk condition), with some variation observed for subjects between 4 and 17 years of age, potentially related to sample size.1

As with all retrospective studies, results can only establish association and not causal relationships.1 There is a potential for miscoding or misclassification of claims and lack of clinical detail or insight into confirmation of influenza through testing.1 Finally, the study sample was largely commercial or self-insured; findings may not be representative of the uninsured, Medicare or Medicaid populations.1

These data published in Vaccine were also presented at the recent National Foundation for Infectious Disease (NFID) 2020 Virtual Annual Conference on Vaccinology Research (ACVR).[8]

About Seasonal Influenza 

Influenza is a common, contagious seasonal respiratory disease that may cause severe illness and life-threatening complications in some people.2 Influenza can lead to clinical symptoms varying from mild to moderate respiratory illness to severe complications, hospitalization and in some cases, death.2 The CDC recommends annual vaccination for individuals aged 6 months and older, who do not have any contraindications.3Because 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.2 Preliminary estimates from the CDC report that from October 1, 2019, through April 4, 2020, there have been an estimated 410,000 to 740,000 influenza-related hospitalizations in the U.S.[9] 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.3 The CDC recommends that people get vaccinated by the end of October.10 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.[10] 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

About Vaccine

Vaccine is the pre-eminent journal for those interested in vaccines and vaccination. It is the official journal of The Edward Jenner Society and The Japanese Society for Vaccinology and is published by Elsevier

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

[1] Divino, V., Krishnarajah, S., Pelton, S. I., Mould-Quevedo, J., Vamshi Ruthwik, A., DeKoven, M., & Postma M. J. A real-world study evaluating the relative vaccine effectiveness of a cell-based quadrivalent influenza vaccine compared to egg-based quadrivalent influenza vaccine in the US during the 2017–18 influenza season. Vaccine. 2020 Jul 30;S0264-410X(20)30936-1. doi: 10.1016/j.vaccine.2020.07.023.

[2] CDC. (2019). Key Facts About Influenza (Flu). Retrieved from: Accessed August 2020.

[3] CDC. (2019). Key Facts about Seasonal Flu Vaccine. Retrieved from: Accessed August 2020.

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

[5] CDC (2020). Vaccine Effectiveness: How Well Do the Flu Vaccines Work? Retrieved from: Accessed August 2020.

[6] This project has been funded in whole or in part with Federal funds from the Office of the Assistant Secretary for Preparedness and Response, Biomedical Advanced Research and Development Authority, under contract numbers HHSO100200600012C, HHSO100200700030C, HHSO100200900101C and HHSO100201200003I.

[7] CDC (2020). Cell-Based Flu Vaccines. Retrieved from: Accessed August 2020.

[8] NFID (2020). Oral Abstracts. Retrieved from Accessed August 2020.

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

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