The virus that causes Covid-19 could have started spreading in China as early as October 2019, two months before the first case was identified in the central city of Wuhan, a new study showed on Friday.
Officially, the first Covid-19 case was identified on December 8 and linked to Wuhan’s Huanan seafood market. However, the new study by researchers from Britain’s University of Kent pins the most likely date to November 17, saying that it had probably already spread globally by January 2020.
The paper was published on Thursday on the PLOS Pathogens journal.
“Our results suggest that the virus emerged in China in early October to mid-November, 2019 (the most likely date being November 17), and by January, 2020, had spread globally,” the researchers said, adding that it suggests a much earlier and more rapid spread than is evident from confirmed cases.
The research estimates that the virus spread beyond China by January 2020 with the estimated first case in Japan on January 3, 2020, followed by Thailand on January 7, 2020. The researchers said the coronavirus is likely to have left eastern Asia and arrived in Europe, with the first case estimated to have come on January 12, 2020, in Spain. It then appeared in South Korea on January 14.
From Europe, the virus may have spread to North America with the first infection estimated to be in the US by January 16, the research suggests.
China has maintained that it has shared all relevant data on the origin of Covid-19 during the investigation conducted by the World Health Organisation (WHO). The Chinese foreign ministry has been on a diplomatic overdrive suggesting that the WHO should investigate the origin in other countries, including in the US, which, according to the study, was the fifth country where the virus most likely spread to.
Doubts over the origin, however, remain, and new studies have raised new questions.
In a paper released on a preprint platform this week, Jesse Bloom of the Fred Hutchinson Cancer Research Centre in Seattle recovered deleted sequencing data from early Covid-19 cases in China, Reuters reported. The data showed that samples taken from the Huanan market were “not representative” of Sars-CoV-2 as a whole and were a variant of a progenitor sequence circulating earlier, which spread to other parts of China.
“Why would scientists ask international databases to delete key data that informs us about how Covid-19 began in Wuhan?” said Alina Chan, researcher, Harvard’s Broad Institute.
