Sinovac Biotech Ltd. (NASDAQ: SVA) ("Sinovac" or the "Company"), a leading provider of biopharmaceutical products in China, announced that the inactivated COVID-19 vaccine candidate developed by Sinovac Life Sciences (Sinovac LS), or "CoronaVac," shows good safety and immunogenicity on healthy adults aged 60 and above from its phase I/II clinical studies conducted in China, which is comparable to the result in healthy adults aged from 18 to 59 in the earlier studies.

The phase I/II clinical trial on elderly volunteers were randomized, double-blinded and placebo controlled trials with two-dose immunization scheduled at 28 day intervals.

CoronaVac was tested on a total of 421 healthy adults aged between 60 to 89 years old in the phase I/II clinical trial. The vaccine candidate appeared to be well tolerated for low dose, medium dose, and high dose groups. No vaccine-related serious adverse event was reported. Both the seroconversion rate and GMT level for elderly volunteers were comparable to the adult group aged 18 to 59 years old. According to the results, the medium dose was selected to enter into phase III trial. The seroconversion rate and GMT for the medium dose group was 98.0% and 42.2 in elderly volunteers, respectively; and 97.4% and 44.1 in healthy adults. The detailed data will be published in a peer reviewed journal.

Mr. Weidong Yin, Chairman, President and CEO of Sinovac, commented, "I am very pleased that our vaccine candidate shows promising results, especially on elderly volunteers who are a highly vulnerable group impacted by the COVID-19 pandemic. As Sinovac is accelerating its vaccine development against the fast spread of the virus, we have completed the construction of our production facility and have commenced production of CoronaVac. Sinovac remains committed to the development of vaccines to fight against the coronavirus."

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 (EV71), hepatitis A and B, seasonal influenza, Quadrivalent Influenza vaccine ("QIV"), H5N1 pandemic influenza (avian flu), H1N1 influenza (swine flu), varicella vaccine 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, and a SARS-CoV-2 (commonly referred to as COVID-19) vaccine. Sinovac primarily sells its vaccines in China, while also exploring growth opportunities in international markets. The Company is registering its products in over 30 countries outside of China.