The sheer scale and speed of China’s effort ratchets up pressure on the U.S., where President Donald Trump’s administration has launched a program called Operation Warp Speed to accelerate vaccine research and development. Xi has promised to share any successful vaccine globally, and the Chinese president would wield immense geopolitical clout if his country produces one of the world’s first working shots.

In total, five vaccines developed by Chinese companies are being tested on humans, the most in any country. Beijing has mobilized its health authorities, drug regulators and research institutes to work around the clock with local companies. Communist Party leaders are overseeing some vaccine trials. Government and private equity money has gone into companies like Beijing-based Sinovac Biotech Ltd., which in May began the second stage of testing for its vaccine.

The Chinese efforts were on show late Friday, when an early-stage study published in the medical journal, The Lancet, showed that an experimental vaccine from China’s CanSino Biologics Inc. was safe and generated an immune response. It’s too early to predict the product’s eventual success and investors beat down CanSino’s stock amid concerns it could have shortcomings.