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Seasonal Influenza Activity Increasing Across Europe - H3N2 Dominant Strain

Basel, Switzerland (ots/PRNewswire)

- Tamiflu Remains Fully Effective Against 94 Percent of
Circulating Influenza Viruses in Europe
Latest surveillance data coming through the European Centre for
Disease Prevention and Control (ECDC) from virologists and clinicians
indicates that the influenza A(H3N2) virus is the predominant strain
in Europe so far this season. Based on the data published by ECDC
Roche confirms that the oral antiviral Tamiflu (oseltamivir) is fully
active against influenza A(H3N2) and influenza B, which currently
comprise 94 percent of circulating viruses in Europe this year.(1)
Tamiflu resistance reported in the 2008-2009 influenza seasons is
confined to H1N1. No resistance has been seen with other circulating
seasonal viruses - H3N2 and influenza B.
"Recent media reporting has elevated awareness of the H1N1
seasonal resistance seen this year in the United States and the Far
East. However, in Europe the picture is different with H3N2 being the
dominant strain so far. The circulating H3N2 viruses, which often
cause a more severe illness than H1N1, are sensitive to oseltamivir,
which means that oseltamivir will be active against the vast majority
of influenza infections in Europe this season, if current trends
continue," comments Prof Albert Osterhaus, Head of Virology, Erasmus
Medical Centre, Rotterdam. "It is important that doctors understand
that oseltamivir remains an effective treatment for patients across
Europe."
Vaccines are considered first line in the management of seasonal
influenza, however, people who show symptoms or have been in close
contact with an infected person may require more immediate
intervention, such as Tamiflu, which can rapidly treat and prevent
influenza.
European surveillance data
The ECDC reports that in the 2008-2009 season, influenza activity
is increasing rapidly across Europe. The first countries to report
high intensity of influenza activity were Portugal and Ireland. To
date, medium or high intensity activity has been reported in nineteen
countries.(1) Of 2488 viruses which have been typed and sub-typed in
Europe so far this influenza season, the majority, 2128, were H3N2,
with a smaller proportion,141, subtype H1N1 and 219 were type B. The
data to date indicate that influenza A (H3N2) and B viruses which
Tamiflu is active against make up over 90 percent of the viruses
circulating in Europe based on the latest information.(1)
US surveillance data
While influenza A(H1N1) has been the most common strain
circulating in the US so far this season, the Centers for Disease
Control and Prevention (CDC) has noted that it is early in the flu
season and it is difficult to predict this season's dominant strain.
Last season in the US, the dominant influenza strain changed from
H1N1 to H3N2 in late January.
In December 2008, the CDC issued interim guidance for the
2008-2009 influenza season which recommends treatment with either
zanamavir or Tamiflu in combination with rimantadine when influenza
A(H1N1) virus infection or exposure is suspected.(2) The CDC has
reminded clinicians to remain alert for additional changes in
recommendations as the influenza season progresses.
At the same time ECDC noted that the epidemiological situation
was different in Europe and that therefore the same considerations
might not apply in Europe. Infections with influenza A(H3N2), the
predominant strain in Europe this season, or B viruses can be treated
with either Tamiflu or zanamavir.
In addition to monitoring by government agencies, WHO
collaborating laboratories and other public health institutions,
Roche recently initiated the global Influenza Resistance Information
Study (IRIS), which will include 1,200 patients per influenza season
from 2008-2011. Roche also continues to support the activities of the
Neuraminidase Inhibitor Susceptibility Network (NISN).
Sensitivity of H5N1 (bird flu) to Tamiflu
Recently published data confirms that the H5N1 avian influenza
(bird flu) strain remains sensitive to Tamiflu. Greater than ninety
nine percent of H5N1 samples studied did not exhibit mutations that
confer oseltamivir resistance.(3)
According to Benjamin Schwartz, MD, CDC National Vaccine Program
Office, "the mutations that have made the H1N1 virus resistant are
unlikely to occur in a pandemic virus, so therefore we have not
changed our recommendations for planning and stockpiling".(4) Tamiflu
remains the World Health Organization's "primary recommended
antiviral agent of choice for the treatment of A(H5N1) virus
infections".(5)
References
(1) EISS - Weekly Electronic Bulletin Week 2
:05/01/2009-11/01/2009 16 January 2009, Issue No 287
(2) The Centres for Disease Control and Prevention (CDC). Interim
Antiviral Guidance for 2008-09
http://www2a.cdc.gov/HAN/ArchiveSys/ViewMsgV.asp?AlertNum=00279
Accessed 6 January 2009
(3) Hill AW et al. Evolution of drug resistance in multiple
distinct lineages of H5N1 avian influenza. Infections, Genetics and
Evolution. 2008
(4) 'Cost, resistance aired in HHS webcast on antivirals'. CIDRAP
News. December 17 2008 http://www.cidrap.umn.edu/cidrap/content/influ
enza/panflu/news/dec1708webinar.html Accessed 16 January 2009
(5) Clinical management of human infection with avian influenza
A(H5N1) virus. World Health Organization. 15 August 2007 http://www.w
ho.int/csr/disease/avian_influenza/guidelines/ClinicalManagement07.pd
f  Accessed 16 January 2009
BASEL, Switzerland, January 19 /PRNewswire/ --
http://www.roche.com

Contact:

International Communications, Manager, Helen Walicka, Tel.
+41(0)79-263-9701

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