Sinovac Temporarily Blocks Access to Its Websites BEIJING

Sinovac Temporarily Blocks

Access to Its Websites

BEIJING, April 30, 2018 /PRNewswire/

-- Sinovac Biotech Ltd. (NASDAQ: SVA) ("Sinovac " or the "Company"), a leading provider of biopharmaceutical

products in China, today announced that Aihua Pan, the Chairman of the Board of the Company's controlled Chinese subsidiary,

Sinovac Biotech Co., Ltd. ("Sinovac Beijing"), who was appointed by Sinobioway Biomedicine Co., Ltd. ("Sinobioway"),

the minority shareholder of Sinovac Beijing, inappropriately and without authorization seized control of the Company's websites,

www.sinovac.com and www.sinovac.com.cn. Out of an abundance of caution, the Company has temporarily blocked the

access to the websites to avoid any further unauthorized access or tampering that could mislead any interested stakeholders.

The misappropriation of the Company's websites is another

blatant attempt by Mr. Pan and Sinobioway to interfere with Sinovac's business.

The Company advises all regulators, shareholders, customers,

employees, and other interested stakeholders that authorized English messages from the Company will be distributed via the Company's

PR Newswire account and filings with the U.S. Securities and Exchange Commission and authorized Chinese messages from the Company

will be distributed via the Company's official WeChat public account (account name: SinovacBiotech) until the Company regains

control of its websites.

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.

Safe Harbor Statement

This announcement may include certain statements that are not

descriptions of historical facts, but are 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

terminology such as "will," "expects," "anticipates," "future," "intends," "plans,"

"believes," "estimates" and similar statements. Forward-looking statements involve risks, uncertainties and

other factors that could cause actual results to differ materially from those contained in any such statements.

Sinovac Biotech Ltd.

Tel: +86-10-8279-9871

Fax: +86-10-6296-6910

Tel: +86 10 6583 7510