Bengaluru: China may have been the origin point of Covid-19 but it is Europe that spread it around the world, a study has said.
Led by scientists from the UK’s University of Huddersfield and Portugal’s University of Minho, the research is based on an analysis of the genetic sequence of 27,000 SARS-CoV-2 genomes.
The study was published in a special edition of the peer-reviewed journal, Microorganisms, on 29 October.
“Whilst the source of Covid-19 was clearly in China, the spread of the global pandemic during the first six months was largely fueled by the expansion in Europe,” state the authors in their paper, adding that travel restrictions in the continent were “too little and too late”.
According to the authors, although the European Union (EU) was closed to outsiders on 17 March, the borders between member countries remained open with varying restrictions. The UK, the researchers pointed out, implemented strict travel restrictions only in June 2020.
“We highlighted how some (countries) were more effective than others in slowing down the spread, but also by unequivocally demonstrating that none were wholly effective in halting the spread,” the authors write.
“Air travel has clearly been a major driver of the pandemic, and our analysis suggests that stricter travel restrictions appear to be more effective in slowing the spread.”
The Covid map
The research was led by clinical geneticist Dr Teresa Rito and evolutionary geneticist Dr Pedro Soares of University of Minho. The duo has collaborated previously with the University of Huddersfield’s Professor Martin Richards and Dr Maria Pala, as part of the Archaeogenetics Research Group, which works on tracing the evolution of humans using genetic analyses.
For the new study, genetic samples of the virus until May were obtained from all over the world using the open-access genomic database GISAID. The researchers then used the data to create a map depicting the spread of the virus.
While the early cases in China all contained genomes with certain mutations, it is the ones that ended up in Europe that branched off to the rest of the world, the researchers said. By mid-March, Europe had become the epicentre for the pandemic before it shifted to the US, which, the researchers said, was primarily infected by travellers coming from Europe.
In April, they added, Europe also saw many newer cases coming in from North America.
Most parts of East Asia also saw cases coming from Europe rather than China, the researchers stated. Even in India, a genomics-based study by the Indian Institute of Science said this June, the majority of Covid-19 cases came from Europe, West Asia, South Asia, and Oceania.