UOA05-12: Revolution in influenza vaccine production
Submitting InstitutionUniversity of Oxford
Unit of AssessmentBiological Sciences
Summary Impact TypeTechnological
Research Subject Area(s)
Medical and Health Sciences: Clinical Sciences, Immunology, Medical Microbiology
Summary of the impact
Research from the University of Oxford has played a major role in the
development of effective vaccines to combat the urgent worldwide problem
of influenza. This methodology, licensed to AstraZeneca, has been used to
prepare the currently licensed live attenuated influenza vaccine FluMist.
Since its introduction in 2006 it is estimated that FluMist or other
vaccines produced using reverse genetics have saved the lives of thousands
of people worldwide who would otherwise have died from flu and its
complications. FluMist has generated close to $1 billion income for the
manufacturers (MedImmune, owned by AstraZeneca).
The World Health Organization estimates that 250,000 to 500,000 deaths
occur worldwide every year from flu-related illnesses. There is therefore
an urgent need for improved production of effective vaccines. Classical
`reassortant' techniques used for virus design and production are
inefficient, time consuming (taking several months) and frequently
In 1998, Professor Ervin Fodor joined the research group of Professor
George Brownlee at the University of Oxford and, working in collaboration
with Drs Palese and Garcia-Sastre (Mount Sinai School of Medicine, New
York), devised a method for producing a wide range of influenza viruses
within the laboratory. The breakthrough was the successful generation of
recombinant influenza viruses after plasmid transfection using reverse
genetics1, 2. It surprised many people in 1999, and still
surprises scientists now, that it was possible to transfect twelve
independent plasmids into a single cell.
Fodor and colleagues' new method resulted in the release of recombinant
influenza viruses by the transfected cells after only a few days. By
virtue of this method, and because manipulation of DNA plasmids is now
routine, any desired mutation can be introduced into any of the eight
individual RNA segments comprising the influenza RNA genome. This approach
has made the development of new vaccine strains rapid and straightforward.
In 2003, collaborations between the University of Oxford and Dr Subbarao
at the Centre for Disease Control, Atlanta, resulted in a pivotal paper
showing the use of plasmid-based viral rescue in the first successful
attempt to prepare a vaccine candidate against H5N1 flu virus3.
There is widespread fear that this highly pathogenic avian flu virus could
adapt to permit human-to-human spread, resulting in a new global flu
pandemic. Such a pandemic has not so far emerged, but work by the
University of Oxford researchers and their collaborators has repeatedly
shown that vaccines which are effective in protecting chickens and mice
against H5N1 bird flu virus4, 5 can be produced using this
The key research achievement was the ability to prepare recombinant
influenza virus easily within the laboratory. In addition to the practical
aims of improving vaccines, the new methodology has accelerated basic
research into influenza by providing a better understanding of (i) the
influenza virus RNA polymerase promoter and its regulation, (ii) the
proteins and domains involved in viral replication, and (iii) the
determinants of virulence. These insights have opened up new avenues for
drug development by the pharmaceutical industry.
References to the research
1. Fodor E, Devenish L, Engelhardt OG, Palese P, Brownlee GG,
García-Sastre A. (1999) Rescue of influenza A virus from recombinant DNA.
Journal of Virology 73: 9679-9682.
original study describing the development of the reverse genetics
technology to generate recombinant influenza virus by transfecting 12
plasmids into Vero cells (derived from green monkey kidney), a cell
line licensed for the production of vaccines for use in humans.
2. García-Sastre A, Palese P, Brownlee GG, Fodor E. (2003) Helper-free
rescue of negative strand RNA virus. United States Patent 6649372.
http://www.google.com/patents/US6649372 This patent described
the invention and its potential applications.
3. Subbarao K, Chen H, Swayne D, Mingay L, Fodor E, Brownlee G, Xu X, Lu
X, Katz J, Cox N, Matsuoka Y. (2003) Evaluation of a genetically modified
reassortant H5N1 influenza A virus vaccine candidate generated by
plasmid-based reverse genetics. Virology 305: 192-200. doi:
10.1006/viro.2002.1742 This study applies reverse genetics to
generate a candidate vaccine against highly pathogenic H5N1 avian
influenza as proof of principle. It also reports that the method
allows the genetic modification of the virus to eliminate determinants
of high pathogenicity, an important safety consideration during
4. Nicolson C, Major D, Wood JM, Robertson JS. (2005) Generation of
influenza vaccine viruses on Vero cells by reverse genetics: an H5N1
candidate vaccine strain produced under a quality system. Vaccine 23:
2943-2952. doi: 10.1016/j.vaccine.2004.08.054 This study describes
the generation of a candidate vaccine against the highly pathogenic
H5N1 influenza virus in Vero cells licensed for human vaccine
production under quality controlled conditions. It also demonstrates
the short time frame in which a seed vaccine can be produced using the
novel reverse genetics technology.
5. Chen Z, Wang W, Zhou H, Suguitan AL Jr, Shambaugh C, Kim L, Zhao J,
Kemble G, Jin H. (2010) Generation of live attenuated novel influenza
virus A/California/7/09 (H1N1) vaccines with high yield in embryonated
chicken eggs. Journal of Virology 84: 44-51. doi: 10.1128/JVI.02106-09 This
study demonstrates that the method can be used to introduce mutations
into the genome of the vaccine virus leading to improved yields in
subsequent viral production.
Funding for research: Research was supported by a £1.1M MRC
Programme Grant to Professor Brownlee.
Details of the impact
Research and development pioneered within the University of Oxford
revolutionised the laboratory production of viruses, enhancing the speed,
specificity, reliability and safety of vaccine production. The innovative
reverse genetics technology resulted in the rapid production (within a few
days) of quantities of virus suitable for use as a vaccine6 and
was invaluable for the development of the FluMist vaccine formulation for
the 2008 flu season7.
A further crucial advantage of the reverse genetics technology pioneered
by Oxford is the ability to mutate any nucleotide in the plasmids used for
the expression of the viral RNA genome segments. This enables the design
of new, ever more effective viruses. The advantage of producing `custom'
viruses was highlighted when insertion of a mutation into the H1N1 vaccine
strain, proved to be critical for increasing the virus yield in the
commercial production of the successful vaccine used in the 2009 bird flu
outbreak6. These achievements - optimising the yield of the
FluMist vaccine and genetically engineering the bird flu multibasic
sequence - would have been highly problematical using the old
`reassortant' technology. Oxford's technology provides an essential tool
to combat future influenza pandemics.
The reverse genetics technology developed by the University of Oxford and
collaborators was licensed to AstraZeneca and MedImmune Inc. (later part
of AstraZeneca) for use in the preparation of FluMist vaccine8.
MedImmune later also non-exclusively licensed the technology to other
companies such as Novartis and Sanofi Pasteur. FluMist was the first
intranasal vaccine, containing the highly attenuated live flu virus (A/Ann
Arbor/ 6/60), able to infect and successfully immunise people against
influenza A and B viruses without causing disease. Later vaccine
developments using the Oxford technology included the cold-adapted LAIV
(tri-valent vaccine currently marketed as FluMist) and FluMist
FluMist as an intra-nasal rather than an injectable vaccine has been
shown to be highly successful9,10 and is marketed worldwide. Already
administered to immunocompetent children from the age of two in the USA,
FluMist (licensed under the name Fluenz in the EU) is to be offered to all
such children from the age of two to 17 in Europe in 2012/311.
Results from a clinical trial have shown the further promise of FluMist as
a vaccine for children from the ages of 5 to 17 years who are
immunocompromised with cancer12. In 2012 a new vaccine, FluMist
Quadrivalent, prepared using reverse genetics technology, was licensed for
use in children, adolescents and adults (two to 49 years of age) in the
USA13. This vaccine, which contains an additional attenuated
virus, should offer even broader protection against flu.
Over 5 years, several million people worldwide have been vaccinated with
the FluMist vaccine that uses the reverse genetics technology. In the UK
alone, annual outbreaks of seasonal flu affect 5 to 20% of the population,
and flu-related deaths vary from 3,300 to 48,860 per annum. Thus,
extrapolating from the UK figure of 562 people dying from flu in 2009 in a
UK population of 60 million, it is estimated that vaccination would
probably have saved the lives of hundreds of people. Flu also has
particularly serious consequences for the elderly. In excess of £22M is
spent on hospital care for the elderly every winter and influenza also
results in more than 400,000 GP appointments annually in England and
Wales. In addition to healthcare costs, flu also places a heavy burden on
productivity and the economy. More than 6 million working days are
estimated to be lost in the UK due to seasonal influenza every year. This
is even before the potential problems of global flu epidemics with the
attendant problems of increased virulence are taken into account. The
"economic savings" made from vaccination are therefore significant,
although very difficult to estimate with any accuracy.
MedImmune announced FluMist sales of $104M in 2008, $145M in 2009 and
$174M in 2010, plus $389M in 2009 and $39M in 2010 of pandemic vaccine
against H1N1. Total sales revenue is thus close to $1 billion since 200814.
Royalties arising from the University of Oxford patents, which were
jointly filed with the US collaborators (licensed by Isis, the Technology
Transfer Office of the University of Oxford, to Mount Sinai School of
Medicine, New York, who licenced it to MedImmune) have already provided
income of over £3M to the University of Oxford.
Sources to corroborate the impact
- Broadbent AJ, Subbarao K. (2011) Influenza virus vaccines: lessons
from the 2009 H1N1 pandemic. Current Opinion in Virology 1: 245-262.
doi:10.1016/j.coviro.2011.08.002 This review article summarises
the benefits of the reverse genetics technology and its impact for
the production of vaccines against the 2009 swine-origin pandemic
- Roumeliotis G. Medlmmune cleared to offer Flumist the reserve genetics
treatment. in-PharmaTechnologist.com. 13 Jul 2006. Available from:
Link between reverse genetics and the future production of
- MedImmune. MedImmune announces FDA approval of first four-strain flu
vaccine, FluMist Quadrivalent (influenza vaccine live, intranasal)
[internet)]. Gaithersburg (MD): U.S. MedImmune; 29 Feb 2012. Available
Website reporting FDA approval for intranasal FluMist.
- Centers for Disease Control and Prevention. The nasal-spray flu
vaccine (live attenuated influenza vaccine [LAIV]) [Internet]. Atlanta:
Centers for Disease Control and Prevention. Available from:
http://www.cdc.gov/flu/about/qa/nasalspray.htm Website of
the CDC describing the efficacy of FluMist.
- Carter NJ, Curran MP. (2011) Live attenuated influenza vaccine
(FluMist; Fluenz): a review of its use in the prevention of seasonal
influenza in children and adults. Drugs 71: 1591-622. doi:
10.2165/11206860-000000000-00000 Paper describing the
effectiveness of FluMist/Fluenz compared with an injectable flu
- AstraZeneca Global. European Commission approves nasal spray vaccine
FLUENZ for the prevention of seasonal influenza in children [Internet].
U.S. AstraZeneca Global; 1 Feb 2011. Available from: http://www.astrazeneca.com/Media/Press-releases/Article/AstraZeneca-approves-nasal-spray-vaccine-Fluenz-for-flu
Press release describing the use of Fluenz in children in Europe.
- Halasa N, Englund JA, Nachman S, Weinberg GA, Huber VC, Allison K,
Dubovsky F, McCullers JA, Flynn PM. (2011) Safety of live attenuated
influenza vaccine in mild to moderately immunocompromised children with
cancer. Vaccine 29: 4110-4115. doi: 1016/j.vaccine.2011.03.097 Paper
describing the safety the FluMist vaccine in immunocompromised
children with cancer.
- AstraZeneca Global. FDA approves first four-strain flu vaccine
[Internet]. U.S. AstraZeneca Global; 1 Mar 2012. Available from: http://www.astrazeneca.com/Media/Press-releases/Article/20120301--fda-approves-first-fourstrain-flu-vaccine
Website reporting Food and Drugs Administration approval for
- AstraZeneca. Therapy area review. Infection AstraZeneca; 2011.
AstraZeneca annual report and form 20-F Information. Available from: http://www.astrazeneca-annualreports.com/2011/documents/pdfs/infection.pdf
Financial reports from AstraZeneca describing sales of