Sinovac Announces Positive Results From Phase III Trial Of a Sabin Strain-Based Inactivated Polio Vaccine (sIPV) Published in the Journal of Infectious Disease

Sinovac Biotech Ltd. (SVA) ("Sinovac" or the "Company"), a leading
provider of biopharmaceutical products in China, today announced that
the positive results from the Company’s Phase III clinical study of a
Sabin strain-based inactivated polio vaccine (sIPV) developed by Sinovac
were published in the Journal of Infectious Disease. With Sinovac’s
sIPV, efficacy is maintained while common risks associated with legacy
vaccines can be mitigated. In comparison to oral polio vaccine (OPV),
inactivated polio vaccine (IPV) contains no live virus and thus carries
no risk of vaccine-derived poliovirus (VDPV) emergence or
vaccine-associated paralytic polio (VAPP). The study found that the
immune responses against the three types of poliovirus in the studied
sIPV were not inferior to those achieved with the control IPV and
demonstrated a good safety profile.

This research implies that the studied sIPV is as effective as IPV in
preventing poliovirus infection in infants aged 60–90 days, can be a
reliable alternative to conventional IPV and can be a good supplement to
OPV in potentially preventing or minimizing VDPV emergence or VAPP.
Participants in the sIPV arm of the trial developed neutralizing
antibodies against poliovirus types 1, 2, and 3 with seroconversion
rates of 98.0% against type 1 poliovirus, 94.8% against type 2, and
98.9% against type 3. Seroconversion rates were higher in the sIPV arm
than in the IPV arm against all three types, significantly so against
types 1 and 2. Participants in the IPV arm developed neutralizing
antibodies against poliovirus types 1, 2, and 3 with seroconversion
rates of 94.1% against type 1, 84.0% against type 2, and 97.7% against
type 3.

“Sinovac’s sIPV carries higher immunogenicity with a lower biosafety
risk, and demonstrates both long-term affordability and accessibility in
comparison to conventional IPV, which is still inaccessible to many
parts of the world, particularly in middle- and low-income countries. If
approved, Sinovac’s sIPV can contribute to the fight for polio
eradication in developing countries and the progress towards a
polio-free world,” said Weidong Yin, Chairman, President and CEO. “We
are very pleased with the sIPV clinical trial results and are grateful
to the participants, their caregivers, and the staff of Guanyun and
Pizhou centers for Disease Control and Prevention. Sinovac’s sIPV
demonstrated superior results to those of IPV and we look forward to
continuing the development of this critical vaccination and discussing
these results with agencies worldwide.”

This study was a randomized controlled, double-blinded, noninferiority
trial investigating the immunogenicity and safety of Sinovac’s sIPV. The
study enrolled 1200 healthy infants ages 60-90 days that were randomly
assigned at a ratio of 1:1 to receive 3 doses of either sIPV or IPV at
days 0, 30, and 60. The safety of the vaccine was assessed for 30 days
after each injection. The study was conducted in Pizhou City and Guanyun
County in Jiangsu Province, China, from August 2017 to January 2018.

About Sinovac

Sinovac Biotech Ltd. is a China-based biopharmaceutical Company that
focuses on the research, development, manufacturing and
commercialization of vaccines that protect against human infectious
diseases. Sinovac's product portfolio includes vaccines against
enterovirus71, or EV71, hepatitis A and B, seasonal influenza, H5N1
pandemic influenza (avian flu), H1N1 influenza (swine flu), and mumps.
Healive, the hepatitis A vaccine manufactured by the Company has passed
the assessment under WHO Prequalification procedures in 2017. The EV71
vaccine, an innovative vaccine developed by Sinovac against hand foot
and mouth disease caused by EV71, was commercialized in China in 2016.
In 2009, Sinovac was the first company worldwide to receive approval for
its H1N1 influenza vaccine, which it has supplied to the Chinese
Government's vaccination campaign and stockpiling program. The Company
is also the only supplier of the H5N1 pandemic influenza vaccine to the
government stockpiling program. The Company is developing a number of
new products including a Sabin-strain inactivated polio vaccine,
pneumococcal polysaccharides vaccine, pneumococcal conjugate vaccine and
varicella vaccine. Sinovac primarily sells its vaccines in China, while
also exploring growth opportunities in international markets. The
Company has exported select vaccines to over 10 countries in Asia and
South America. For more information please see the Company’s website at www.sinovacbio.com.

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