CAMBRIDGE, Mass., April 19, 2018 /PRNewswire/ — Seqirus, a CSL company (ASX: CSL) and a leading innovator in influenza vaccines, today announced that The Lancet Respiratory Medicine published results from a Phase 3, randomized, head-to-head efficacy study that found an MF59® adjuvanted, quadrivalent influenza vaccine (aQIV) 31 percent more efficacious in preventing influenza than a non-adjuvanted conventional influenza vaccine in children aged 6 through 23 months.

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Published results also demonstrated aQIV, which protects against two influenza A and two influenza B strains, induced a superior immunogenic response, as measured by Geometric Mean Titers (GMTs), in children aged 6 months through 5 years against both vaccine matched and mismatched strains.2

«Influenza and its complications pose a serious public health threat to young children, especially those under 2 years of age,» said Dr. Vesikari, MD, PhD, University of Tampere Medical School and lead author of the study. «Because traditional influenza vaccines are less efficient in producing a robust immune response in young children, improved vaccines are urgently needed for this vulnerable group.»

Annual influenza-related hospitalizations among U.S. children younger than the age of 5 have ranged from 7,000 to 26,000 since 2010, and annual reported influenza-related deaths in children 18 years and under have ranged from 37 to 171 during regular influenza seasons in the same time span, according to the U.S. Centers for Disease Control and Prevention (CDC).3

Gregg Sylvester, MD, Head of Medical Affairs for Seqirus said «Seqirus is committed to reducing influenza-related death and hospitalizations through the development of more effective influenza vaccines. The findings published today in Lancet Respiratory Medicine offer compelling evidence that the very young, who are most vulnerable to influenza, may significantly benefit from an aQIV vaccine option.»

About the Study

The phase III study was led by Dr. Vesikari and sponsored by Seqirus during the 2013-2014 and 2014-2015 influenza seasons. The study involved 10,644 children aged 6 months through 5 years who received one or two doses of aQIV or a non-adjuvanted influenza vaccine.

Endpoints included Reverse transcription polymerase chain reaction (RT-PCR) confirmed, culture-confirmed and antigenically matched influenza, and immunogenicity against homologous and heterologous strains of influenza A and/or B. Significant relative vaccine efficacy was demonstrated in children 6 through 23 months of age (relative vaccine efficacy 31·37, 95% CI 3·14–51·38), but not in the overall study population (relative vaccine efficacy –0·67, 95% CI –19·81 to 15·41).All endpoints were pre-specified for both overall age group and the subgroup aged 6 through 23 months.

Published results also demonstrated aQIV, which protects against two influenza A and two influenza B strains, induced a superior immunogenic response, as measured by GMTs, in children aged 6 months through 5 years against both homologous and heterologous strains.2  The majority of study enrollment was conducted primarily during a season in which a mismatch occurred between the vaccine A/H3N2 strain and the circulating A/H3N2 strain.

The published study can be accessed here.

About MF59®

MF59®, a proprietary adjuvant for which Seqirus has an exclusive license in flu, is an oil-in-water squalene-based emulsion. Squalene, a naturally occurring substance found in humans, animals and plants, is highly purified for the vaccine manufacturing process. Studies have shown that adjuvants such as MF59 can improve influenza vaccines to provide a more potent immune response in young children and older adults.2,4,5

About Seqirus

Seqirus is part of CSL Limited (ASX:CSL), headquartered in Melbourne, Australia. The CSL Group of companies employs more than 20,000 people with operations in more than 60 countries.

Seqirus was established on July 31, 2015 following CSL’s acquisition of the Novartis influenza vaccines business and its subsequent integration with bioCSL. 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 and response.

Seqirus operates state-of-the-art production facilities in the US, the UK and Australia, and manufactures influenza vaccines using both egg-based and cell-based technologies. It has leading R&D capabilities, a broad portfolio of differentiated products and a commercial presence in more than 20 countries.

Media Contact

David Minella
Seqirus US
+ 1 (919) 802 7641


  1. Neuzil KM, Zhu Y, Griffin MR, et al. Burden of interpandemic influenza in children younger than 5 years: a 25-year prospective study. J Infect Dis 2002; 185: 147–52.
  2. Vesikari T, Kirstein J, Go GD, Ruzycky ME, Isakov L, de Bruijn M, Oberye J and Heijnen E. Efficacy, immunogenicity, and safety evaluation of an MF59-adjuvanted quadrivalent influenza virus vaccine compared with non-adjuvanted influenza vaccine in children: a multicentre, randomised controlled, observer-blinded, phase 3 trial. Lancet Respir Med 2018; S2213-2600(18)30108-5
  3. National Center for Immunization and Respiratory Diseases. «Flu Vaccine for Preteens and Teens.» Available at:
  4. Vesikari T, Knuf M, Wutzler P, Karvonen A, Kieninger-Baum D. Oil-inwater emulsion adjuvant with
  5. influenza vaccine in young children. N Engl J Med 2011;365:1406-1416.
  6. Cheong HJ, Song JY, Heo JY, et al. Immunogenicity and Safety of the Influenza A/H1N1 2009 Inactivated Split-Virus Vaccine in Young and Older Adults: MF59-Adjuvanted Vaccine versus Nonadjuvanted Vaccine. Clinical and Vaccine Immunology : CVI. 2011;18(8):1358-1364. doi:10.1128/CVI.05111-11.

MF59® is a registered trademark of Novartis AG.

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