W ang Jilei is a Chinese billionaire whose wealth is derived from his family's stake in the biopharmaceutical company, Sinovac Biotech. His father, Wang Ke, was a co-founder of the company. Sinovac, which is headquartered in Beijing, focuses on the research, development, and manufacturing of vaccines for human infectious diseases. The company had a portfolio of vaccines for diseases like hepatitis and influenza, but it became a major global name during the COVID-19 pandemic.

Sinovac developed CoronaVac, an inactivated virus COVID-19 vaccine, which became one of the most widely used vaccines in the world, particularly in China and in many other developing countries across Asia, Latin America, and Africa. The massive global sales of the CoronaVac vaccine during the pandemic led to a huge surge in the company's revenue and valuation, a financial windfall that turned the founding families, including Wang Jilei and his father, into billionaires.