Sinovac Reports Preliminary Top-Line Results from Phase III Clinical Trial for Varicella Vaccine Candidate Against Chickenpox

-- Phase III Preliminary Results Demonstrate Vaccine Efficacy Rate of87.1%

BEIJING, September 25, 2017 /PRNewswire/ -- Sinovac Biotech Ltd. (SVA), a leading provider of vaccines in China, announced today preliminary top-line data from its Phase III clinical trial assessing the efficacy, immunogenicity and safety of the Company's proprietary Varicella vaccine against Chickenpox.

The primary objective of the study was to evaluate the efficacy of the Varicella vaccine in the prevention of Chickenpox caused by Varicella-Zoster Virus (VZV). The preliminary Phase III data showed that Sinovac's Varicella vaccine was 87.1% (95% CI: 69.7%, 94.5%) efficacious against Chickenpox caused by VZV.

The double-blinded, randomized, placebo controlled Phase III clinical trial was conducted at two sites across China's Henan province. Approximately 6,000 healthy children from 1 to 12 years old completed the one dose vaccination schedule in the August of 2016, prior to the Chickenpox epidemic season in China, followed by an active monitoring period.

In parallel, Sinovac conducted another clinical study that was comprised of 1,197volunteers and designed to evaluate the consistency of three consecutive lots of Varicella vaccine manufactured by the Company. The trial was conducted in children from 1 to 3years old. After receiving the vaccine, the ratios of antibody GMTs on the 30th day of any two groups were calculated and the 95% confidence intervals of the ratios were all between 0.67 and 1.5, which indicates that the immunogenicity of the three vaccine lots is consistent. The study results showed consistent immune response for all three lots and a good safety profile. With immunogenicconsistency across the three consecutive lots, the results showed that Sinovac's vaccine production process and quality are stable. The production facility of Varicella vaccine has also reached commercial scale.

Mr. Weidong Yin, Chairman, President and CEO of Sinovac, commented, "We are pleased to report an over 87% efficacy rate from the Phase III trial of our Varicella vaccine. The conclusion of this trial means that we are on track for commercialization by the end of 2019 and marks an important milestone in our goal to commercialize the varicella vaccine. Once commercialized, the Varicella vaccine will be supplied to meet existing market demand and support our subsidiary Sinovac Dalian in strengthening its financial position in the near future."

Sinovac obtained clinical research approval for its proprietary Varicella vaccine candidate from the CFDA in September2015, and completed Phase I clinical trials in 2016. The preliminary results of the Phase I studies confirmed that Sinovac's vaccine candidate has a good safety profile.

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.In addition, an innovative vaccine developed by Sinovac against hand foot and mouth disease caused by EV 71 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 currently 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 10 countries in Asia and South America. For more information, please visit the Company’s website at www.sinovac.com.

Safe Harbor Statement

This announcement contains forward-looking statements. These statements are made under the “safe harbor” provisions of the U.S. Private Securities Litigation Reform Act of 1995. These forward-looking statements can be identified by words or phrases such as “will,”“expects,”“anticipates,”“future,”“intends,”“plans,”“believes,”“estimates” and similar statements. Among other things, the business outlook and quotations from management in this press release contain forward-looking statements. Statements that are not historical facts, including statements about Sinovac’s beliefs and expectations (including with respect to the filing of the2016 Annual Report, the compliance plan, the internal investigation, the SEC enforcement action and the litigation matters discussed above), are forward-looking statements. Forward-looking statements involve inherent risks and uncertainties. A number of important factors could cause actual results to differ materially from those contained in any forward- looking statement. Sinovac does not undertake any obligation to update any forward-looking statement, except as required under applicable law.

Contact

Sinovac Biotech Ltd.
Helen Yang
Tel: +86-10-8279-9871
Fax: +86-10-6296-6910
Email: ir@sinovac.com

ICR Inc.
Bill Zima
U.S: 1-646-308-1707
Email: william.zima@icrinc.com