Coronavirus may have been spreading in Scotland for up to a month before the first confirmed case was recorded by health professionals, the chief medical officer has said.
Dr Gregor Smith revealed experts used “next generation sequencing technology” to establish early examples of Covid-19 spreading at a community level in February.
The technique, which identifies subtle molecular differences between strands of the virus to create “family trees”, revealed Europe was the “main source” of at least 112 separate introductions of the virus into Scotland.
Dr Smith said most strains of Covid-19 analysed from the early weeks of the outbreak are believed to have originated abroad but because “not all of them have travel history”, it is likely community transmission was taking place.
“The use of this next generation sequencing technology has allowed us to identify at least 112 separate introductions of Covid-19 across Scotland that ultimately led to sustained community transmission,” Dr Smith said.
“It has identified viral lineages with no clear link to travel at the very early stages of the outbreak in Scotland, suggesting that there may have been earlier introduction to Scotland and community spread even before the first cases emerged.
“In this respect, the emergence of continental Europe as the global epicentre of the epidemic appears to have been the main source of the particular lineages that have established in Scotland.”
Speaking during the Scottish Government’s daily briefing on Tuesday, Dr Smith said there was no evidence of “widespread” transmission in February and stressed cases were likely to be “very few in number”.
The first confirmed case of Covid-19 in Scotland was announced on March 1 and involved an individual who had recently returned home to Tayside from Italy. The first recorded case of suspected transmission within Scotland was on March 11.
Dr Smith said the evidence suggests an outbreak at a Nike conference in Edinburgh on February 26 was successfully contained because its particular “sub lineage” of the virus had not been detected in Scotland since towards the end of March.
Of the 70 international delegates at the Nike conference in late February, 25 have since tested positive – eight of them in Scotland.
Earlier at the briefing, First Minister Nicola Sturgeon confirmed Scotland had recorded new deaths from coronavirus for the first time in three days.
A total of 2,422 patients have died after testing positive for coronavirus, up seven from Monday, while 15,653 people have tested positive for the virus – a rise of 14.
There were 1,011 people in hospital with confirmed or suspected cases of Covid-19, a decrease of 31, and three fewer patients in intensive care.
Despite the rise in deaths, Ms Sturgeon said the figures were “further indication of a clear downward trend” and she remains optimistic Scotland will be able to lift more lockdown restrictions on June 18.
She said the news is “not what we would have wanted to hear” but “it’s not a surprise, either” as a weekend lag was expected.
The first minister also confirmed initial data from the Scottish Government’s Test and Protect contact-tracing system will be published on Wednesday, including how many new cases have been identified and how many people have had contacts traced.
Ms Sturgeon said there is not yet evidence to suggest people from Bame backgrounds are being disproportionately affected by Covid-19 in Scotland but confirmed she has set up a new “expert reference group” to consider this more fully.
