Dr. Li-Meng Yan wanted to remain anonymous. It was mid-January, and Yan, a researcher in Hong Kong, had been hearing rumors about a dangerous new virus in mainland China that the government was playing down. Terrified for her personal safety and career, she reached out to her favorite Chinese YouTube host, known for criticizing the Chinese government.

Within days, the host was telling his 100,000 followers that the coronavirus had been deliberately released by the Chinese Communist Party. He wouldn’t name the whistleblower, he said, because officials could make the person "disappear.”

By September, Yan had abandoned caution. She appeared in the United States on Fox News, making the unsubstantiated claim to millions that the coronavirus was a bioweapon manufactured by China.