A new genetic study suggests COVID-19 started spreading quickly around the world at the end of last year, according to CNN.

Genetics researchers of the University College London Genetics Institute analyzed sequences of the virus that causes COVID-19 from more than 7,600 patients around the world.

They said viral samples taken from all corners of the globe show similar mutations.

"Our results are in line with previous estimates and point to all sequences sharing a common ancestor towards the end of 2019, supporting this as the period when SARS-Cov-2 jumped into its human host," the research team told CNN.

The analysis shows the virus must have spread extremely quickly after the first infection was reported in Wuhan last December.

Researchers found genetic evidence that supports suspicions the virus was infecting people in Europe, the US and elsewhere weeks or even months before the first official cases were reported in January and February.

It will be impossible to find the "first" patient in any country, said researcher Francois Balloux.

"All these ideas about trying to find a Patient Zero are pointless because there are so many patient zeros," he said.