The Huanan Seafood Market in Wuhan, the epidemic's epicenter, is believed to be the the origin of the novel coronavirus. Photo: cnsphotos

Chinese scientists have discovered a novel coronavirus clade that is different from that shared among patients connected to the Huanan seafood market in Wuhan, which provides new evidence that the market may not be the origin of the virus that caused the deadly COVID-19 pandemic.

Chinese scientists collected viral genome samples from 326 patients in Shanghai between January 20 and February 25. They identified two major clades, both of which included cases diagnosed in early December 2019, according to a pre-review paper published online by Nature magazine on May 20.

They noticed that genomes of six patients with contact history related to the Huanan seafood market fell into one kind of clade while those of three other patients diagnosed in the same period but without exposure to the market clustered into the other clade, suggesting multiple origins of transmission in Shanghai, the paper said.

Two major lineages of the virus deriving from one common ancestor may have originated independently from Wuhan in December 2019 and contributed to the current pandemic, although no major difference in clinical manifestation or transmissibility was found between them, the paper explained.

The study was jointly conducted by research teams from the Shanghai Public Health Clinical Center and the National Research Center for Translational Medicine.

The number of confirmed COVID-19 cases around the world had reached nearly 5.5 million as of 3:30 pm Tuesday.

The Huanan seafood market was previously deemed to be the origin of the novel coronavirus that caused the pandemic, but recent research indicates that the speculation may not be right.

The Huanan seafood market is more like a victim of COVID-19 rather than the origin of the novel coronavirus, Gao Fu, director of the Chinese Center for Disease Control and Prevention (CDC) and member of the National Committee of the 13th Chinese People's Political Consultative Conference, told the media on Monday.

Gao said he had gone to Wuhan to collect samples for COVID-19 researchers in early January, but no viruses were detected in the animal samples. Viruses were only found in environmental samples, including sewage.