Covid Scotland: Number of patients in hospital up 74 per cent to over 1,500

At the peak of Omicron wave in January, the figure was 1,571.

It comes with less than two weeks to go until Scotland is set to end the legal requirement for facemasks in shops, hospitality and public transport from March 21, and amid uncertainty over the provision of free Covid tests from April onwards.

Number of patients "in hospital" with Covid (Source: Scottish Government)

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NHS Lanarkshire - which has seen the number of Covid patients in its hospitals double from 88 in mid-February to 186 now - has reinstated essential visiting only to all its acute wards at Wishaw, Monklands and Hairmyres.

The restriction means that visits are only permitted for patients who would experience "particular distress or suffering" at not seeing a family member.

Professor Christina Pagel, an expert in healthcare mathematics and member of the independent SAGE advisory group, said the surge in Covid hospital admissions - which is also being seen in England - is due to "waning boosters in older people especially" as well as increased prevalence of the more infectious BA.2 sub-lineage of Omicron, which now accounts for more than half of cases in Scotland and around 70% in England.

The BA.2 strain appears to have a "substantial growth advantage" compared to the previously dominant BA.1 strain of Omicron, but there is no evidence that it causes more severe disease.

However, simply being more transmissible - as Omicron was compared to Delta - means it can spread to more people, and this is enough to increase hospitalisations.

Prof Pagel added that reductions in mask-wearing, testing, and self-isolation were also "enabling more infections".

Meaghan Kall, an epidemiologist for the UK Health Security Agency, said waning immunity among the over-70s appeared to be the likeliest explanation since it has "been six months since most were boosted".

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Analysis by the UKHSA indicates that for adults given AstraZeneca for their first two doses - as the majority of over-40s in Scotland were - protection against mild infection with Omicron wanes to 30-40% more than 15 weeks after a booster.

Protection against severe disease, meanwhile, wanes to around 75% by 10 to 14 weeks after a booster.

On Monday, NHS Scotland began its "second booster" rollout, which will see all over-75s, elderly care home residents, and the immunosuppressed offered fourth or fifth vaccine doses 24 weeks after their last jag.

Older patients spend longer in hospital recovering from Covid, which means that bed occupancy is rising faster than admissions

It comes as the latest data from Public Health Scotland shows that infection rates have been rising sharply since early February in the over-60s and over-85s, with increases among younger adults and children not emerging until the end of February.

This reverses previous trends which tended to see spikes in the virus spread up through the generations, suggesting that waning protection from boosters has left older adults more exposed.

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Confirmed cases among care home residents have shot up from 198 in the first week of February to 583 in the first week of March.

Among over-85s in the community, case rates have nearly tripled over the same period, from around 30 to more than 80 per 100,000. For the over-60s age group as a whole case rates had doubled to around 95 per 100,000.

This has started to feed into hospital figures, with weekly admissions for Covid positive patients in the over-75 age group rising by 33% between the first and last week of February - from 220 to 319 - at the same time as admissions for under-50s fell by 4%.

Older patients with Covid are much more likely than younger people to be in hospital "because of" the infection, as opposed to testing positive during admission for other treatment.

They also take far longer to recover. Over-75s diagnosed with Covid spend 10 to 11 days in hospital on average, compared to two to four days for those aged 18 to 39.

This is likely to explain why the increase in hospital bed occupancy - the number of patients "in hospital" with Covid - has been rising much more steeply than admissions.

Covid-related absences among NHS staff are also on the rise, up from around 3,500 in mid-February to more than 4,200 in the past week.