CORONAVIRUS first arrived and began spreading in Scotland during February, according to new genetic research that suggests community transmission was underway weeks earlier than previously thought.

The findings also appear to overturn theories that a Nike sports conference in Edinburgh at the end of February was Scotland’s ‘Ground Zero’ for the infection.

Dr Gregor Smith, Scotland’s interim chief medical officer, said it was unclear exactly when the virus first arrived in Scotland, but that “some form of community transmission was underway in Scotland probably during the month of February”.

He added that the same research indicated that infection control measures had been successful in wiping out any cases linked to the Nike conference by the end of March.

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The first known case of Covid-19 in Scotland was reported on March 1, in a patient in Tayside who had recently returned from a trip to northern Italy - at the time a Covid hotspot.

Sustained community transmission - meaning the infection is being passed widely from person to person within Scotland, without any links to foreign travel - was not confirmed until March 16.

However, scientists have now dated the outbreak to weeks earlier using genomic sequencing.

The technique enables them to unpick subtle, but distinctive, molecular signatures in order to identify different versions - or ‘lineages’ - of the virus circulating in Scotland.

They can then track where each individual lineage is occurring and how fast it is spreading.

Dr Smith said this has “allowed them to identify at least 112 separate introductions of Covid-19 to Scotland that ultimately led to sustained community transmission”.

Within this, they have been able to pick out viral lineages “with no clear link to travel at the very early stages of the outbreak in Scotland”, said Dr Smith.

He said: “What this work tells us is that right back at the start, when we first started experiencing cases in Scotland in the early part of March, although the majority of these cases we were detecting - when you do the genomic sequencing - you could associate them with importations from abroad, not all of them could you clearly determine that there was a travel history.

“What that suggests is that there was some form of community transmission that was underway in Scotland probably during the month of February.

“But it’s difficult to say with any certainty at exactly what point these viruses have been introduced.”

He stressed that this did not necessarily mean that anyone experiencing Covid-like symptoms in February would have been infected due to high levels of flu and other viral pathogens in the environment at the end of winter.

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Even now, nearly 90 per cent of people with symptoms who are tested for the SARS-CoV-2 virus prove negative - although up to a third can be false negatives.

Mr Smith said: “We won’t be able to say with certainty if someone who was experiencing the kinds of symptoms we would associate with Covid 19 - the cough, the fever - was specifically associated with Covid 19.

“At the moment, the best estimates we have from this genome sequencing is that there were probably importations in February, but we can’t say with any certainty other than that when they would have arrived in Scotland.”

The first known cases of coronavirus in the UK were confirmed on January 31, in Chinese tourists visiting York.

A Nike conference held at the Hilton Carlton Hotel in Edinburgh on February 26 and 27 attracted 70 delegates from around the world.

Of the attendees, 25 were later diagnosed with Covid-19, including eight in Scotland.

The Scottish Government has come under fire for not publicising the outbreak earlier. It only came to light following a BBC investigation last month.

Dr Smith said genetic analysis had linked a further three possible cases to the conference, but two have now been discounted while the third “shows similarities with those associated with the conference, but no direct or indirect link to the conference has been established”.

He added: “All show similarities with a viral lineage found in continental Europe.

“However, this particular sub-lineage has not been detected in Scotland since the end of March.

“This suggests that the actions taken by the [infection management team] were successful in curtailing spread and have led to the eradication of this particular viral lineage, with no evidence of any wider outbreak associated with it in Scotland since that time.”

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It comes as a study from Harvard Medical School suggested that the new virus could have emerged in Wuhan, China as far back as September or October last year, based on a “dramatic increase” in traffic to the city’s major hospitals around that time, and a spike in queries on a Chinese internet for “certain symptoms that would later be determined as closely associated with the novel coronavirus.”

China did not formally notify the World Health Organization of the new disease until December 31.

Meanwhile, First Minister Nicola Sturgeon stressed that Scotland is continuing to see a “clear downward trend” in Covid deaths. It came as she reported seven new deaths in patients known to have the virus, after two consecutive days with none. This was attributed to a “weekend lag” in death registrations.