Coronavirus: Puzzle over Scotland's rising intensive care admissions

It comes amid reports that those being admitted to intensive care units in the current wave are "younger and sicker", with links being made to new mutant strains.

READ MORE: Will vaccines get life back to normal in Scotland in 2021?

The more contagious UK variant, believed to have originated in Kent, has gone from having 18 confirmed cases in Scotland before Christmas to accounting for around 80% of new infections now.

INTENSIVE CARE: Admissions were falling steadily until January 28, but have since levelled off and showed signs of increasing

HOSPITAL ADMISSIONS: Overall hospitalisations for Covid have been falling steadily since January 12 and are continuing to fall

A report last week from the UK's the New and Emerging Respiratory Virus Threats Advisory Group (NERVTAG) estimated that the Kent variant is probably 30-70% more deadly than other versions of the virus in circulation.

First Minister Nicola Sturgeon said the intensive care pattern is something Scottish Government experts are "looking at closely".

She said: "They haven't shown that steady, sustained decrease that we've seen in overall hospital cases.

"I'm not sure that we understand it fully."

Cases have been falling steadily since January 8, although in recent days there have been sign of a slowdown

The levelling off and increase in ICU admissions has not been reflected in deaths, which are continuing to fall. However, deaths have been falling most rapidly in over 85s, who have been vaccinated first, while ICU patients tend to be younger

The latest data from Public Health Scotland shows that the average number of new positive cases each day is down 67% since January 8, although there are signs that this decline is slowing.

Overall hospital admissions, which were averaging nearly 197 per day on January 12, have dropped steadily to less than 76 per day now, with deaths nearly halving from around 62 per day to 34 per day in the four weeks to February 14.

Intensive care admissions had been showing a similar steady decline - peaking at a seven-day average of 18 per day on January 18, before falling 43% to 10.3 per day by January 28.

At that point, however, something changed.

Chief Nursing Officer Professor Fiona McQueen said there may be a link between ICU admissions and infections around Christmas caused by the new UK variant

Instead of continuing to fall in line with cases and overall hospital admissions, intensive care admissions suddenly stopped decreasing and began slowly climbing instead.

By February 14, an average of 12.6 patients a day were becoming critically ill and requiring ICU care.

There are currently 125 Covid patients in intensive care, of whom 30 have been receiving treatment for more than 28 days.

That means that Covid patients are continuing to occupy more than half of Scotland's standard intensive care capacity, of 173 beds.

Professor Fiona McQueen, Scotland's chief nursing officer, said the Government still expects to see ICU admission numbers coming down, but added that it was possible they reflect a fallout from increased socialising around Christmas.

She said: "The stagnant numbers at the moment could be - and we need to keep a careful eye on this - but could be that tail from the increase [in mixing] at Christmas, because it can sometimes take four to five weeks for people to go into intensive care following their infection.

"That, combined with the slightly more brittle effect that this variant has on people, could be giving us those figures, but it is something that we're keeping a close eye on."

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Improvements in drug treatments and therapies mean survival rates are now higher among critically ill Covid patients compared to the first wave, which could explain why an increase in admissions is not being reflected in deaths.

It is also possible that deaths among ICU patients, who tend to be younger, are being offset by a much steeper decline among the over-85s as a result of vaccination, with figures this week revealing a 45% drop in deaths for this age group in the past three weeks. 

Source: National Records of Scotland

The most recent Covid patient audit by the Scottish Intensive Care Society only covers a period up to November 14, so there is no clear data to confirm anecdotal reports from frontline NHS staff that they are now treating more people in their 30s and 40s for serious disease.

If this were the case, however, it could mean that the impact of vaccination is felt more slowly in intensive care.

Source: Travelling Tabby site, from Public Health Scotland data

While over-85s have accounted for 40% of Covid deaths in Scotland during the pandemic, the average age of patients admitted to intensive care with the disease between March and November was already lower, at 61 years.

Healthy under-50s will not be given first vaccine doses until May.