Mr. Ebright said the Chinese video shows Wuhan CDC workers under Mr. Tian’s direction with inadequate personal protective equipment and unsafe practices, including exposed faces and wrists and a lack of goggles or face shields.

Such practices “would pose substantial risk of infection with a virus having transmission properties similar to those of the outbreak virus,” he said.

Mr. Ebright said the 2017 news report and 2019 video suggest several possibilities of accidental infection. They include accidental exposure in caves or field laboratories by those without proper protection, accidental infection during transit from caves or field laboratories, accidental infection inside the Wuhan CDC lab because of poor security, and accidental infection during shared work between the Wuhan CDC and the Wuhan Institute of Virology because of inadequate security at the CDC.

Biosecurity researcher Richard Ebright, a Rutgers University professor at the Waksman Institute of Microbiology, said the coronavirus behind the pandemic is 96.2% similar to a bat virus discovered by the Wuhan Institute of Virology in 2013 and studied at the Wuhan CDC.

“Bat coronaviruses are collected and studied by laboratories in multiple parts of China — including Wuhan Municipal CDC and Wuhan Institute of Virology,” he told The Washington Times. “Therefore, the first human infection also could have occurred as a laboratory accident.”

Steven W. Mosher, a China specialist with the Population Research Institute, said China for years has been doing research, detailed in scientific journals, on horseshoe bat coronaviruses that could be harmful to humans.

“They write about collecting SARS-like coronaviruses from horseshoe bats and proving that, like the SARS virus itself, some of these other naturally occurring coronaviruses could infect human beings directly,” Mr. Mosher said. “They write about genetically engineering new and deadly viruses capable of infecting human lung tissue — just like the Wuhan flu does.”