Biogen Idec and Biovitrum Announce Decision to Advance Long-Acting Hemophilia B Therapy into a Registrational Trial

Cambridge, Mass and Stockholm, Sweden - October 19, 2009 - Biogen
Idec (NASDAQ: BIIB) and Biovitrum AB (STO: BVT) today announced that
they plan to advance the companies' long-acting, fully-recombinant
Factor IX Fc fusion protein (rFIXFc) into a registrational clinical
trial in hemophilia B patients. The decision to advance the program
is based on promising data from a Phase I/IIa open-label,
multi-center, safety dose-escalation and pharmacokinetic study of
intravenous rFIXFc in severe, previously-treated hemophilia B
patients. rFIXFc was well tolerated in the study. In addition, rFIXFc
demonstrated a prolonged half-life compared to historical data for
existing therapies, supporting advancement of the program.

Hemophilia B requires frequent injections, creating a significant
burden for the majority of individuals with the disorder. The
potential of rFIXFc, which is based on Biogen Idec's novel and
proprietary monomeric Fc-fusion technology, to prolong protection
from bleeding and reduce the frequency of injections for both
prophylaxis and on-demand therapy will be evaluated in the
registrational trial.

The global trial is being designed to assess the safety,
pharmacokinetics and efficacy of rFIXFc in the prevention and
treatment of bleeding in hemophilia B patients. The trial will
commence following communications with regulatory authorities. rFIXFc
has received orphan medicinal product designation for the treatment
of hemophilia B from both the European (EMEA) and US (FDA)
authorities.

"rFIXFc is an example of Biogen Idec's commitment to developing
innovative therapies to address significant unmet medical needs. The
rFIXFc program has the potential to improve the lives of individuals
with hemophilia B and we are excited about advancing the program,"
said Glenn Pierce, Vice President and Chief Medical Officer of Biogen
Idec's hemophilia therapeutic area.

"The Phase I/II results are very encouraging. The decision to
initiate our first registrational program represents true progress in
our efforts to offer hemophilia B patients treatment that makes a
significant difference and is also an important milestone in the
ongoing development of Biovitrum," said Martin Nicklasson, CEO of
Biovitrum.

About Hemophilia
Hemophilia is a rare, inherited disorder in which the ability of a
person's blood to clot is impaired. Hemophilia B occurs in about 1 in
25,000 male births annually and is caused by having substantially
reduced or no factor IX protein, which is needed for normal blood
clotting. People with hemophilia B therefore need injections of
factor IX to restore the coagulation process and prevent frequent
bleeds that could otherwise lead to pain, irreversible joint damage
and life-threatening hemorrhages. Prophylaxis treatment with
infusions two or three times per week to maintain a sufficient
circulating level of coagulation factor is being increasingly used,
and long-term studies demonstrate that such regimens increase the
patient's life expectancy and greatly reduce if not eliminate
progressive joint deterioration.

About Biogen Idec
Biogen Idec creates new standards of care in therapeutic areas with
high unmet medical needs. Biogen Idec is a global leader in the
discovery, development, manufacturing, and commercialization of
innovative therapies. Patients in more than 90 countries benefit from
Biogen Idec's significant products that address diseases such as
lymphoma, multiple sclerosis, and rheumatoid arthritis. For product
labeling, press releases and additional information about the
company, please visit www.biogenidec.com.

About Biovitrum
Biovitrum is an international pharmaceutical company that markets
specialist pharmaceuticals in several regions globally. The company
head office is located in Sweden. Using its expertise and experience
Biovitrum takes scientific innovation to patients with significant
medical need. Research expertise and capabilities are focused on
development and production of biotechnology therapeutics within our
prioritized areas of hemophilia, inflammation/autoimmune diseases and
malabsorption. The company has revenues of approximately SEK 1.2
billion and around 400 employees. It is listed on the OMX Nordic
Exchange in Stockholm. For more information go to  www.biovitrum.com.

Safe Harbor
This press release contains forward-looking statements regarding the
development of long-acting, recombinant Factor IX Fc fusion as a
potential treatment for hemophilia B. These statements are based on
the companies' current beliefs and expectation. Drug development
involves a high degree of risk. Factors which could cause actual
results to differ materially from

the companies' current expectations include the risk that we may not
fully enroll our planned clinical trials, unexpected concerns may
arise from additional data or analysis, regulatory authorities may
require additional information, further studies, or may fail to
approve the drug, or the companies may encounter other unexpected
hurdles. For more detailed information on the risks and uncertainties
associated with Biogen Idec's drug development and other activities,
see the periodic reports of Biogen Idec filed with the Securities and
Exchange Commission. The companies assume no obligation to update any
forward-looking statements, whether as a result of new information,
future events or otherwise.

Biovitrum AB (publ) may be required to disclose the information
provided herein pursuant to the Swedish Securities Markets Act. The
information was provided for public release on October 19, 2009 at
08:30 a.m. CET.