New analysis dispels theory that said COVID-19 was in circulation long before Dec '19

A new genetic analysis of the novel coronavirus shows it has been circulating in people since late last year, and must have spread extremely quickly after the first infection -- dispelling the speculation that said it was in circulation long before it was recognised.

The samples were taken from more than 7,600 patients around the world.

Researchers at the University College London Genetics, Britain also looked at mutations in the virus and found evidence of quick spread, but no evidence the virus is becoming more easily transmitted or more likely to cause serious disease.

They said the findings indicate that the virus first started infecting people at the end of last year, ruling out any scenario that assumes SARSCoV-2 may have been in circulation long before it was identified, and hence have already infected large proportions of the population.

A few doctors had earlier hoped the virus was circulating for many months and may have quietly infected many more people than has been reported. That would offer the hope that there might be some immunity already built up in some populations.

The first human cases of COVID-19 were reported in Wuhan, China, last December. The virus has since then infected as many as 3.5 million people across the world, and has killed over 2,50,000.