The Wuhan seafood market, which is at the centre of the pneumonia outbreak, has been closed. (Photo: Handout)

A new study by Chinese researchers indicates the novel coronavirus may have begun human-to-human transmission in late November from a place other than the Huanan seafood market in Wuhan.

The study published on ChinaXiv, a Chinese open repository for scientific researchers, reveals the new coronavirus was introduced to the seafood market from another location, and then spread rapidly from market to market. The findings were the result of analyses of genome-wide data, sources of infection and the route of spread of 93 samples of the novel coronavirus collected from 12 countries across four continents.

The study believes that patient zero transmitted the virus to workers or sellers at the Huanan seafood market. The crowded market facilitated the further transmission of the virus to buyers, which caused a wider spread in early December 2019.

According to the researchers, the new coronavirus experienced two sudden population expansions, including one on January 6, 2020, which was related to the Chinese New Year's Day holiday.

An earlier expansion occurred on December 8, implying human-to-human transmission may have started in early December or late November, and then accelerated when it reached the Huanan seafood market.

On January 6, the National Center for Disease Control and Prevention (CDC) issued a second-level emergency response, which the researchers said served as a warning against mass public activity and travel.

If the warnings had received wider public attention, the number of cases spreading nationally and globally in mid-to-late January would have been lower, said the researchers.

Patients from Australia, France, Japan and the US - countries with wider samples - have had at least two sources of infection, and the US in particular has reported five sources, the study said.

However, based upon limited samples in other countries, the source of most infections is deemed to be the same. In addition to their contact history with Wuhan, some may have been infected in South China's Guangdong Province and Singapore.

Global Times