Packaging suspected

In research published in the China CDC Weekly in October, researchers from the China CDC confirmed that the outbreak in Qingdao in October was caused by packaging of imported fish contaminated with the virus. Scientists isolated live novel coronavirus from a package while tracing the COVID-19 outbreak.

Wu Zunyou, chief epidemiologist at the China CDC, said earlier that since it is very possible that several of the COVID-19 outbreaks in China in recent months were caused by imported seafood, people should think about new approaches to tracing the earliest COVID-19 cases linked to the seafood market in Wuhan.

The possibility that the COVID-19 outbreak in Wuhan was caused by imported seafood contaminated with SARS-CoV-2 cannot be ruled out, he said.

Gao, director-general of the China CDC, said he is open to such a view, and "it seems that such a possibility is increasing" with more research and discoveries over the past few months globally.

"Origin-tracing of the virus is a purely scientific matter and should be left in the hands of scientists," Gao said. "Much is still unknown about the virus, and persistent and rigorous scientific efforts must be made on the path to finding the answer."

Such efforts can also contribute to the prevention and control of possible new epidemics or pandemics caused by any new coronavirus that could emerge in the future, he said.