Medivir Announces Positive Phase 2b 48-week (SVR24) Interim Results of TMC435 in Treatment-Naive Patients Chronically Infected With Genotype-1 Hepatitis C Virus

HUDDINGE, Sweden, February 22, 2011 - Medivir AB (OMX: MVIR), the emerging research-based specialty
pharmaceutical company focused on infectious diseases, announces today
further positive results from the phase 2b PILLAR (C205) study of TMC435 in
treatment-naive patients with hepatitis C virus (HCV) genotype-1.

    - TMC435 was safe and well tolerated with no clinically
      relevant differences in adverse events between treatment groups and
      standard of care (SoC).
    - In the TMC435 treatment groups 83% of patients were able to stop
      all therapy at week 24
    - Potent and consistent antiviral efficacy was demonstrated with
      SVR24 rates of up to 84%

"We are very pleased by both the efficacy and safety shown by
TMC435 in this 48-Week interim analysis. With the additional features of once
daily dosing, TMC435 also has a more convenient and competitive dosing
regimen" stated Bertil Samuelsson, CSO of Medivir. "The recently published
start of three global phase 3 clinical trials is an important milestone in
the continued development of TMC435. We are now looking forward to the
48-week interim data from the phase 2b trial C206 (ASPIRE) in
treatment-experienced patients during Q2 2011."

The 48-week interim results from the 5-arm phase 2b response
guided PILLAR study in 386 treatment-naive patients showed further consistent
high antiviral activity, and the good safety and tolerability previously
demonstrated was confirmed. The 24-week (EOT) interim results were presented
at the AASLD conference in Boston, MA, in November 2010.

Study design

In the PILLAR study, 75mg or 150mg TMC435 was given for either
12 or 24 weeks in combination with 24 weeks of ribavirin and pegIFNalpha-2A,
the current standard of care (SoC). Patients in the TMC435 arms stopped all
treatment at week 24 if certain predefined response-guided criteria were met.
In the TMC435 treatment groups 83% of patients were able to stop all therapy
at week 24. Patients who did not meet the above response-guided criteria
continued with SoC until week 48 as did the placebo group.

Evaluation criteria

A protocol-defined interim analysis was performed when all
patients completed their Week 48 visit or discontinued treatment earlier.
Final SVR4 and SVR24 data were available for 98% (303/309; n/N) and 93%
(288/309; n/N) of TMC435 treated patients, respectively. SVR24 is determined
24 weeks after the planned end of treatment (EoT) and was therefore not yet
available for the patients in the placebo group and for some of those in the
TMC435 group who received 48 weeks of treatment. SVR4, which is determined 4
weeks after the planned EoT, was available for 77% (59/77; n/M) of the
patients in the placebo group.

Results - Efficacy

Potent and sustained antiviral efficacy was demonstrated in
the SVR4 and SVR24 rates with no major differences between TMC435 doses or
length of triple therapy. At week 4 after cessation of treatment 87.2%,
86.5%, 84.9% and 88.5% of patients taking TMC435 and Peg-IFN/RBV (SoC)
achieved undetectable HCV RNA levels. At week 24 after cessation of treatment
83.6%, 76.1%, 83.1% and 84.4% of patients taking TMC435 and Peg-IFN/RBV (SoC)
achieved undetectable HCV RNA levels, i.e. SVR24. At week 4 after cessation
of treatment 71.2% in the placebo SoC group had achieved undetectable HCV RNA
levels.

The results are derived from an intent-to-treat (ITT) analysis
of the patient population who took at least one dose of the study medication
and who reached the criteria for stopping all treatment at 24 weeks (83%).

    Sustained Virological Response 4 and 24 Weeks after Planned End of
    Treatment (EoT);

             TMC435       TMC435       TMC435       TMC435       Placebo
             12PR24       24PR24       12PR24       24PR24
             75mg q.d.    75mg q.d.    150mg q.d.   150mg q.d.
    % (n/N)  N=78         N=75         N=77         N=79         N=77
    SVR4     87.2 (68/78) 86.5 (64/74) 84.9 (62/73) 88.5 (69/78) 71.2 (42/59)
    SVR24    83.6 (61/73) 76.1 (51/67) 83.1 (59/71) 84.4 (65/77) N/A

* < 25 log10 IU/mL undetectable

q.d.: once daily, PR: pegIFNalpha-2A and ribavirin,

SVR4 and SVR24: patients with undetectable HCV RNA 4 and 24 weeks after
planned EoT, respectively. N/A: Patients in the control arm continue SoC
until Week 48 and SVR24 data was not available

Results - Safety and Tolerability

TMC435 was generally safe and well tolerated and overall
incidence of adverse events (AEs) was similar across treatment groups. AEs
leading to discontinuation of TMC435 or placebo treatment were reported in
7.8% of the placebo subjects and in 7.1% of the TMC435 treated subjects. In
the safety analyses, special attention was given to the following AEs of
interest: hepatobiliary AEs, pruritus, rash, anemia, and cardiac events. For
each category of AEs of interest; the incidence was similar between TMC435
and placebo.

In laboratory parameters, there were no clinically relevant
differences between any TMC435 groups and placebo except for mild on
treatment reversible bilirubin elevations (total, direct and indirect) in the
150 mg TMC435 arm, which were normalized after TMC435 dosing was completed.
There were no meaningful differences between treatment groups for any of the
other laboratory parameters. Significant and rapid decreases in transaminases
(ALT and AST) were observed in all TMC435 treatment groups.

Conference Call For Analysts and Investors:

There will be a conference call today, February 22 2011, for
investors and sell-side analysts at 09:00 (EDT) / 14:00 (GMT) / 15:00 (CET)
with the management team of Medivir to discuss this announcement. To dial-in
to the conference call please use the following numbers:

    Participant Telephone Numbers:
    +1-718-354-1385 USA
    +46(0)8-5352-6408 Sweden
    +44(0)20-7806-1951 UK
    Confirmation Code: 6641746

Alternatively, please contact Lindsey Neville at M:Communications on Tel:
+44(0)207-920-2333, Email: Neville@mcomgroup.com.

Notes to Editors

About TMC435 in other clinical studies

TMC435 is a once-daily (q.d.) protease inhibitor drug jointly
developed by Medivir and Tibotec Pharmaceuticals, to treat chronic hepatitis
C virus infections.

    The clinical phase 3 program started recently including

    - TMC435-C208 or QUEST-1 includes approximately 375
      treatment-naive patients
    - TMC435-C216 or QUEST-2 includes approximately 375 treatment-naive
       patients
    - TMC435-C3007 or PROMISE includes approximately 375 who have
       relapsed after prior interferon-based treatment

In parallel to the recent start of the global phase 3-studies,
TMC435 is currently in a follow up phase in three phase 2b clinical trials
(TMC435-C205, TMC435-C206 and TMC435-C215) in G1 treatment-naive and in G1
patients that failed previous IFN-based treatment. More safety and efficacy
data from the phase 2b trials will be presented at scientific meetings later
in 2011.

A phase 3 program for TMC435 has also recently been launched in Japan.

For additional information for these studies, please see
www.clinicaltrials.gov

About Hepatitis C

Hepatitis C is a blood-borne infectious disease of the liver
and is a leading cause of chronic liver disease and liver transplants. The
WHO estimates that nearly 180 million people worldwide, or approximately 3%
of the world's population, are infected with hepatitis C virus (HCV). The CDC
has reported that almost three million people in the United States are
chronically infected with HCV.

About Medivir

Medivir is an emerging research-based specialty pharmaceutical
company focused on the development of high-value treatments for infectious
diseases. Medivir has world class expertise in polymerase and protease drug
targets and drug development. Medivir has a strong R&D portfolio and has
recently launched its first product Xerese(TM)/Xerclear(R). Medivir's key
pipeline asset, TMC435, a protease inhibitor, recently entered global phase 3
development for the treatment of hepatitis C and is partnered with Tibotec
Pharmaceuticals.

Xerese(TM)/Xerclear(R) is an innovative treatment for cold
sores, which has been approved in both the US and Europe. It is partnered
with GlaxoSmithKline to be sold OTC in Europe and Russia and with Meda AB in
North America. Medivir has retained the Rx rights for Xerclear(R) in Sweden
and Finland.

For more information on Medivir, please see the company
website: www.medivir.com

    For additional information, please contact

    Medivir (www.medivir.se)

    Rein Piir, CFO & VP Investor Relations
    Mobile: +46-708-537-292
    M:Communications

    Europe: Mary-Jane Elliott/ Amber Bielecka /Nick Francis
    Medivir@mcomgroup.com
    +44(0)20-7920-2330

    USA: Roland Tomforde
    +1-212-232-2356

For additional information, please contact: Medivir (www.medivir.se); Rein Piir, CFO & VP Investor Relations, Mobile: +46-708-537-292, M:Communications; Europe: Mary-Jane Elliott/ Amber Bielecka /Nick Francis, Medivir at mcomgroup.com, +44(0)20-7920-2330; USA: Roland Tomforde, +1-212-232-2356