As the outbreak worsened in January and officials in Wuhan imposed a lockdown, Lin Wenhua, a freelance videographer in the city, pivoted from producing advertisements to using his camera to document the crisis.

Mr. Lin, 38, posted videos of his conversations with doctors and nurses who described not having time to rest, and with homeless workers displaced by the epidemic. He attracted a following of more than five million people on Weibo, one of China’s most popular social media sites, even as several of his videos were deleted by government censors.

“Human nature has been magnified in this crisis,” he said. “You see warm and kind characters, but you also see especially ugly ones.”

A few young people have channeled their experiences on the ground into explicitly political appeals.

Li Zehua, a former host on China Central Television, the state broadcast agency, traveled to Wuhan to cover the outbreak as a citizen journalist, interviewing stranded migrant workers and crematory workers. In his last video, Mr. Li, 25, urged his peers to learn more about China’s history.

“I’m not willing to disguise my voice, nor am I willing to shut my eyes and close my ears,” he said before two men in plainclothes entered his apartment and the video was cut off. “I hope more young people can stand up!”

Mr. Li has not been heard from since, nor has Chen Qiushi, another young citizen journalist in Wuhan.