Sinovac Biotech Ltd. is a Chinese biopharmaceutical company based in Haidian District, Beijing that focuses on the research, development, manufacture, and commercialization of vaccines that protect against human infectious diseases. The company was listed on the Nasdaq but the exchange halted Sinovac's trading in February 2019 due to a proxy fight. The company has faced bribery probes in China. Its COVID-19 vaccine was the target of a covert disinformation campaign by the US government and a promotional social media astroturfing campaign by the Chinese government. Wikipedia