NICOLA Sturgeon has rejected claims made by Gordon Brown’s think tank that Scotland’s coronavirus testing regime is underperforming.

According to a report by Our Scottish Future, only around a third of Scotland’s cases are being picked up by tests.

The group compared daily rates for positive coronavirus tests to an average of Office for National Statistics' (ONS) estimates of the total number of people who had the virus.

Over a six-week period ending January 2, the ONS estimated a daily average of around 43,379 people in Scotland had Covid-19, including asymptomatic cases, based on statistical modelling of population samples.

Over the same time period, Scotland's testing programmes picked up a rolling average of 13,650 cases.

Our Scottish Future says this means 32% of the total cases are being picked up – with the equivalent figure for England being 41%, while Wales was at 70% and Northern Ireland at 81%.

READ MORE: Gordon Brown's Our Scottish Future accused of undermining confidence in Covid system

However, during Tuesday’s coronavirus briefing, Sturgeon said using this methodology with more up to date figures would mean Northern Ireland – where the number of positive results returned from tests is higher than the average taken from ONS data – would be greater than 100%. 

The First Minister said: “We have significant issues with the methodology, which would mean we would question the conclusions about Scotland's performance here compared to others.

“More generally, though not every person with Covid in the country features in our confirmed cases because not everybody gets tested, so there is always an assumption that the true level of infection is higher than the numbers we are reporting here every day and that is all factored into the modelling we do about what we expect to see happen, what the pressure on our health service is going to be.” 

The First Minister said there would always be a gap between the number of people tested positive or self-isolating and the true prevalence of the virus. 

She added: “What we’ve tried to do to narrow that gap is doing more widespread community mass testing in order to pick up more asymptomatic cases of the virus because the asymptomatic nature of some people's virus is one of the main reasons why they don't get tested because they don't have the symptoms and therefore they don't go for testing.

“So we did some pilots before Christmas, and we're now looking at doing much greater scale community mass testing initiatives which will not completely eradicate that gap, but will help us close that gap.” 

READ MORE: Covid in Scotland: Death toll passes grim milestone as another 54 people die

Scotland’s national clinical director branded the report “unfair”. 

Jason Leitch said: “They've confused prevalence, which is how much disease you have in your country which is a model number you can't ever know, no country can know, so that that's got big confidence intervals around it statistically, with incidence, which is how much you have from your positive tests, how many new cases you find each day. 

“They've then subtracted one from the other, and come up with a percentage, as if that is how much we find. 

“I don't think that's fair. I don't think it's statistically correct, either.”

He added: “But the fundamental truth is that you want to find as much disease as you can, and isolate it from the rest of the community, and you do that in two ways. 

“You do that by testing and contact tracing. We don't test every contact because we want that disease, out of circulation, we want in homes, self isolated, and that's where we do very, very well. Our contact tracing has got very high percentages within 24 to 48 hours, and our testing results come back, very very quickly. 

“So I'm very confident that the fundamental premise of this document which says test and protect isn't working, is actually false.”