The spread of the novel coronavirus in France has no link with imported cases from China, according to a genetic study made public by France's Pasteur Institute.
The institute released the news on Tuesday that the epidemic in France was caused by a locally circulating strain whose origin is still unknown, and it has published the findings in a paper on the website bioRxiv.org.
Researchers have sequenced 97 virus samples collected between Jan 24 and March 24 from infected patients in France, and they confirmed that the first cases on Jan 24 in France were directly linked to the cases from Hubei, China.
However, the later predominant circulation of the epidemic in many French regions has no link to the cases in January since France took effective measures to curb its spread, but it is caused by a locally circulating virus, according to the paper.
The viruses in China and France are from the same ancestor, but they are in two different clades. The paper describes the virus in France as clade G, which mainly caused the steep increase of cases reported in many affected regions.
The first sample of clade G was collected on Feb 19 from a patient who had no history of travel or contact with returning travelers, according to the paper, which implied that the virus had been silently circulating in France in February.
Researchers were unsure where this virus comes from and how long it has been circulating in France as it was not detected because of the large proportion of infected individuals showing mild or no symptoms.
