The dominant strains of the coronavirus in Russia came from Europe instead of China due to the timely closure of the China-Russia border, scientists have said.
The study of over 200 viral samples obtained in March and April by researchers in Moscow and St Petersburg concluded the first identified cases were linked to China.
But while early border closures with China prevented further transmission, strains that later came from Europe triggered a wider outbreak, according to the team led by Georgii Bazykin, a professor at Skolkovo Institute of Science and Technology in Moscow.
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The paper, which is the first study of Covid-19 genomic epidemiology in Russia, was posted on the preprint service medRxiv.org on Friday and has yet to be peer-reviewed.
Russia has the fourth largest number of confirmed cases in the world, which stood at over 777,400 on Monday, according to statistics from the World Health Organisation, including more than 12,000 deaths.
The findings were based on analysis of genome sequences from 211 samples, mainly collected in St Petersburg and Moscow. They were obtained between March 11 and April 23, during which confirmed cases in the country surged from 28 to over 60,000.
However, only four, or 2 per cent, of the samples belonged to strains which were widespread in Asia, while the rest all corresponded to those dominating in Europe, the study found.
The main sources were France, Britain, Denmark and Sweden, it said.
Genomic epidemiology study helps scientists learn how the virus transmits from one person to another, said Bazykin.
“For example, imagine that Russia opens its borders, and case counts start to rise. Is this a coincidence, or do those cases originate from a newly imported virus? By comparing the genomes of new and old viruses, we will be able to tell,” Bazykin said in a statement issued by the institute.
“Our analysis suggests that the border closure with China implemented in February has effectively curbed the virus introduction into Russia from the Asian direction,” the paper said.
The Russian government imposed quarantine for travellers from China on January 23, just a few days after Chinese authorities announced human-to-human transmission was happening. It closed the land border with China and cancelled most incoming flights a week later.
This was possibly why the outbreak of local cases occurred in Russia later than in many European countries, the researchers said.
However, that did not mean the coronavirus that causes the disease had come from outside China, said Jin Dong-yan, a biochemistry professor with the Li Ka-shing Faculty of Medicine at the University of Hong Kong.
“The viral diversities in China and Europe are only slightly different. The strains widespread in Europe originally came from China. They just mutated into new forms gradually,” he said.
“That’s why we found the strains in the recent outbreak in Beijing can be traced to Europe, but we don’t say Europe started this pandemic.”
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This article Coronavirus: dominant strain in Russia came from Europe after Chinese border was closed first appeared on South China Morning Post