The U.S. government is investigating whether the Covid-19 virus came from a government laboratory in Wuhan, China. The Chinese Communist Party denies the possibility. “There is no way this virus came from us,” claimed Yuan Zhiming over the weekend. Mr. Yuan is a top researcher at the Wuhan Institute of Virology, which studies some of the world’s deadliest pathogens. He is also secretary of the lab’s Communist Party committee. He accuses me of “deliberately trying to mislead people” for suggesting his laboratory as a possible origin for the pandemic.

Beijing...