The new CSL Seqirus-developed vaccine will be introduced to the annual influenza vaccination programme from next year (2027/28).
Its introduction marks a significant advance in the evolution of seasonal influenza prevention for adults aged 65 years and over as well as at-risk adults aged 50 to 64 years who are more vulnerable to the complications of influenza.
This is the first influenza vaccine to combine three proven approaches to enhancing protection for older adults in a single vaccine: MF59^®adjuvant, cell-based manufacturing, and a higher dose formulation, compared to standard influenza vaccines.
Together with the world-first introduction of aTIVc, the UK Health Security Agency (UKHSA) has extended its pandemic Advance Purchase Agreement (APA) with CSL Seqirus for a further four years through to 2031, reinforcing its influenza pandemic and outbreak preparedness and response capability that leverages its vaccine manufacturing site in Liverpool.

MAIDENHEAD, England, Sept. 22, 2026 /PRNewswire/ -- CSL Seqirus, a business of CSL (ASX: CSL; USOTC: CSLLY), today announced a strengthened partnership with the UK Government that will see the UK become the first country in the world to introduce AUJEMFLU (aTIVc), CSL Seqirus' adjuvanted cell-based seasonal influenza vaccine, from the 2027/28 influenza season, alongside an extended pandemic preparedness Advance Purchase Agreement (APA) that leverages the UK's largest and only end-to-end vaccine manufacturing at its Liverpool site in northern England.¹

Recommended by the Joint Committee on Vaccination and Immunisation (JCVI) for adults aged 65 years and over as well as at-risk adults aged 50 to 64 years, the vaccine combines three proven approaches to enhancing protection in older adults: MF59^® adjuvant, cell-based manufacturing and a higher dose formulation, compared to standard influenza vaccines.²

Each of these approaches has been used separately in influenza vaccines for many years and is supported by extensive clinical and real-world evidence. This publication provides the first large-scale evaluation of their combination within a single vaccine.³

Influenza remains a significant public health challenge, causing substantial illness, hospitalisations and deaths each year despite widespread vaccination programmes.⁴ Older adults are particularly vulnerable because the immune system becomes less responsive with age, reducing its ability to mount a strong protective response following vaccination.⁵

aTIVc combines three proven approaches to enhancing vaccine protection in older adults, with each playing a distinct role.⁶^,⁷^,⁸ Cell-based manufacturing helps preserve a closer match to circulating influenza strains.⁸ MF59^® adjuvant strengthens, broadens and lengthens the immune response and a higher dose formulation further enhanced that response.³

Gregg Sylvester, Chief Medical Officer and Head of Research & Development at CSL Seqirus, said: "This significant milestone builds on our decades of influenza vaccine innovation and reflects our ongoing commitment to advancing influenza prevention. By bringing together our proven MF59^® adjuvant and cell-based technologies in a higher-dose formulation, this new enhanced vaccine represents a significant advance in our portfolio of differentiated influenza vaccines. We are proud to support the UK's national immunisation programme in helping protect people against influenza and reduce pressure on health services each winter."

Despite the positive impact of the annual vaccination programme in the UK, which is estimated to have prevented 104,000 hospital admissions and 7,100 deaths in England during winter 2025/26, influenza continues to place a significant burden on older adults, vulnerable populations and health services.³

According to the latest figures from the UK Health Security Agency (UKHSA), there were an estimated 3,798 excess deaths associated with influenza in England during the 2025/26 season.³

Regulatory approval for aTIVc was supported by a pivotal, peer-reviewed Phase 3 randomised immunogenicity and safety study published last week in The Lancet Infectious Diseases. The large-scale study enrolled 7,699 adults aged 50 years and older across eight countries and compared aTIVc with two enhanced influenza vaccines.² The study demonstrated:

Superiority versus the adjuvanted egg-based influenza vaccine comparator across all four influenza strains and age groups assessed.
Non-inferiority versus a recombinant influenza vaccine for three out of four strains in the 50+ age group and four out of four strains in those aged 65+.
Immune responses that persisted throughout the influenza season.
A well-tolerated safety profile. Most reactions were mild or moderate and resolved within three days.²

The vaccine will be manufactured through CSL Seqirus' global influenza vaccine network, with the final stages of production taking place at the company's Liverpool site. The site is central to CSL Seqirus' long-standing partnership with the UK Government, NHS and UK Health Security Agency, combining seasonal influenza vaccine supply with its pandemic and outbreak preparedness capability that can be rapidly leveraged through world-class manufacturing.

Dame Diana Johnson, Minister of State for Public Health and Patient safety, said: "Every winter, flu affects millions of families across the country, with older people among those particularly at risk. That's why I'm proud that the UK is due to be the first country in the world to roll out a new vaccine next year targeted at older age groups along with existing vaccines."

"By extending our pandemic preparedness partnership with CSL Seqirus, we are safeguarding the nation's future health security, supporting skilled jobs and backing manufacturing in Liverpool, demonstrating how partnership with industry can drive both economic growth and better health outcomes."

Professor Adam Finn, an international vaccine expert from the University of Bristol, said: "Combining cell-based flu vaccine technology and adjuvanted flu vaccine technology into one vaccine is an obvious next step in the development pathway. This also provides an opportunity to optimise the doses of both flu antigens and adjuvant to maximise protection while having an acceptable safety profile. The recommendation to include this new formulation in the flu vaccine programme from 2027 represents a useful new addition to the options now available to protect the elderly and other adults at high risk of severe flu."

Marc Lacey, Global Executive Director, CSL Seqirus, said: "This strengthened partnership with the UK Government brings together a world-first vaccine introduction and a unique pandemic preparedness offering rooted in world-class manufacturing in northern England. By combining the UK's adoption of aTIVc with an extended Advance Purchase Agreement to support pandemic readiness, we are helping to protect people each winter while maintaining the capability to respond rapidly to a future influenza pandemic from our Liverpool site."

Nigel Hilton, Site Head, Liverpool and Global Head of Manufacturing, CSL Seqirus, said: "Bringing a new influenza vaccine from development through to large-scale manufacture is a significant undertaking. We are proud that Liverpool will play a key role in supplying this new enhanced vaccine, supporting the UK's influenza vaccination programme while strengthening the resilience of influenza vaccine supply through our global manufacturing network. The Liverpool site will also continue to support the UK's pandemic preparedness and response capability through the renewed Advance Purchase Agreement and remains central to CSL Seqirus' long-standing partnership with the UK Government."

CSL Seqirus' adjuvanted egg-based vaccine (aTIV) will continue to be available for the upcoming 2026/27 UK influenza season. The company's announcement today enables healthcare providers to begin ordering aTIVc for the 2027/28 season as planning and pre-ordering activities are now underway.

The announcement positions the UK-CSL Seqirus partnership at the intersection of seasonal vaccine innovation and pandemic readiness: the UK will be the first country in the world to introduce aTIVc, while CSL Seqirus and UKHSA have extended their influenza pandemic preparedness agreement for a further four years. Under the renewed advance purchase agreement (APA), the UK Government would have the option to purchase more than 100 million doses of pandemic influenza vaccine from CSL Seqirus should a WHO-declared influenza pandemic occur, with manufacturing based entirely at the company's Liverpool facility.

For more information, please contact:
MEDIA CONTACT
Alex Kiefer
Alex.Kiefer@Seqirus.com
Director International & Pandemic Communications, CSL Seqirus

Notes to Editors:
About aQIVc
aQIVc is an MF59^® adjuvanted, cell-based higher-dose quadrivalent influenza vaccine developed for adults aged 50 years and older. The trivalent formulation has been licensed for use in people aged 50 and above in the UK and by the European Commission where it is marketed as AUJEMFLU^®.

The vaccine combines three proven approaches designed to enhance protection in older adults:

MF59^® adjuvant technology
Cell-based manufacturing
A higher dose formulation versus standard dose influenza vaccines
Each dose contains 45 micrograms of haemagglutinin per influenza strain and 19.5 mg of MF59^® adjuvant⁸

About the Phase 3 Study
The randomised, observer-blind Phase 3 immunogenicity study enrolled 7,699 adults aged 50 years and older across Canada, Denmark, Estonia, Germany, Pakistan, the Philippines, the United Kingdom and the United States. Participants received either the MF59^®-adjuvanted cell-derived higher dose quadrivalent vaccine, an MF59 adjuvanted egg-based quadrivalent influenza vaccine or a recombinant quadrivalent influenza vaccine. The study evaluated immunogenicity, safety and manufacturing consistency.

About Advance Purchase Agreements (APAs)
Advance Purchase Agreements (APAs) are preparedness arrangements designed to support rapid access to vaccines and other medical countermeasures in the event of future public health emergencies. By establishing key supply and planning principles in advance, APAs help governments and public health authorities strengthen pandemic preparedness, enhance resilience, and support a coordinated response when needed. Such agreements form an important part of broader strategies to safeguard public health and improve readiness for emerging infectious disease threats.

About Pandemic Influenza Vaccines
Influenza is a contagious airborne respiratory disease. The risk of influenza-associated morbidity and mortality is greater with pandemic influenza than with seasonal influenza because there is likely to be little or no pre-existing immunity to the novel virus in the human population. The timing and severity of pandemic influenza is unpredictable. Four influenza pandemics have occurred over the past century, with the 1918 pandemic being the most severe in recent history, with an estimated mortality of up to 50 million people worldwide. Strain-matched pandemic influenza vaccines are manufactured in response to the declaration of a pandemic and an Advance Purchase Agreement (APA) provides access to a reserved quantity of vaccine.

About CSL Seqirus
CSL Seqirus is part of CSL (ASX: CSL). As one of the largest influenza vaccine providers in the world, CSL 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 US, the UK and Australia, CSL Seqirus utilises egg, cell and adjuvant technologies to offer a broad portfolio of differentiated influenza vaccines in more than 20 countries around the world. For more information about CSL Seqirus, visit www.CSL.com.

About CSL Seqirus Liverpool
CSL Seqirus Liverpool is the only injectable influenza vaccine manufacturing facility in the UK and one of the largest biotechnology sites in Europe. Employing more than 1,000 production workers, it is a centre of excellence for the manufacture of enhanced influenza vaccines, with bulk manufacturing capability and expanded fill and finish lines enabling the efficient production of seasonal influenza vaccines for both northern and southern hemispheres. It also plays a key role in global biosecurity, providing pandemic preparedness and response to the UK, other countries in Europe, and the World Health Organisation (WHO).

Intended Audience
This press release is issued by CSL Seqirus and is intended to provide information about our global business. Information relating to the approval status, product labels, recommendations and availability of CSL Seqirus products may vary from country to country. Please consult your local regulatory authority for information on approval status and local prescribing information.

Forward-Looking Statements
This press release may contain forward-looking statements, including statements regarding future results, performance, regulatory milestones, product availability or achievements. These statements involve known and unknown risks, uncertainties and other factors which may cause actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements. Given these uncertainties, you should not place undue reliance on forward-looking statements.

GBR-aTIVc-26-0042

References

¹ CSL Seqirus. On the Front Line of Influenza Protection: Liverpool backgrounder. September 2024. GBR-NOPR-24-0073. Liverpool: CSL Seqirus; 2024. Available on file.
² GOVUK. DHSC. JCVI statement on influenza vaccines for 2027 to 2028. Available online: https://www.gov.uk/government/publications/flu-vaccines-2027-to-2028-jcvi-advice-16-july-2026/jcvi-statement-on-influenza-vaccines-for-2027-to-2028 Accessed August 2026.
³ Essink BJ, Vermeulen W, Andrade C, Mazur M, de Rooij R, Heijnen E, et al. Immunogenicity and safety of an MF59-adjuvanted cell-derived higher-dose quadrivalent influenza vaccine (aQIVc) in adults aged 50 years or older: a phase 3 randomised controlled trial. Lancet Infect Dis. In press 2026. Volume 26. Available online: https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(26)00410-X/abstract September 2026. THELANCETID-D-26-00167R3.
⁴ GOVUK. UKHSA. Influenza in the UK, annual epidemiological report: winter 2025 to 2026. Available online: https://www.gov.uk/government/statistics/influenza-in-the-uk-annual-epidemiological-report-winter-2025-to-2026/influenza-in-the-uk-annual-epidemiological-report-winter-2025-to-2026 Accessed August 2026.
⁵ Doherty TM, Weinberger B, Didierlaurent A, Lambert PH. Age-related changes in the immune system and challenges for the development of age-specific vaccines. Ann Med. 2025 Dec;57(1):2477300. doi: 10.1080/07853890.2025.2477300. Epub 2025 Mar 20. PMID: 40110678; PMCID: PMC11926906. Available online: https://pmc.ncbi.nlm.nih.gov/articles/PMC11926906/ Accessed August 2026.
⁶ Pulendran, B., S. Arunachalam, P. & O'Hagan, D.T. Emerging concepts in the science of vaccine adjuvants. Nat Rev Drug Discov 20, 454-475 (2021). Available online: https://www.nature.com/articles/s41573-021-00163-y#citeas Accessed August 2026
⁷ Ashraf M, Stein AN, Youhanna J, et al. The impact of egg adaptation and immune imprinting on influenza vaccine effectiveness. Vaccine. 2025;62:127393.
⁸ Aujemflu suspension for injection in pre-filled syringe: summary of product characteristics [Internet]. Maidenhead: Seqirus UK Limited; 4 June 2026 (PL 47991/0020). Available from: https://www.medicines.org.uk/emc/product/102343/smpc Accessed September 2026.

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