Covid Scotland: One in three patients admitted to hospital is over 75

This includes patients hospitalised because of infections, and people who test positive while in hospital for other treatment.

Hospital admissions with Covid

The figure is up from 1,034 the previous week, but marks a significant slowdown compared to the 15 per cent and 8% week-on-week increases seen since February.

Of those admitted to hospital in the most recent week, 368 (35%) were over 75 and 342 (33%) were under 50.

Around half of patients under 50 with Covid will spend less than 24 hours in hospital, but older patients take much longer to recover - driving an increase in bed occupancy.

The latest daily data shows that 1,999 patients are currently in hospital with Covid, the highest number since early January 2021.

The statistical update from PHS also highlighted a surge in the proportion of cases being caused by the more transmissible BA.2 sublineage of Omicron.

Omicron BA.2 (green) is now dominant in Scotland

The strain, which accounted for 84.2% of cases in Scotland by March 11, is estimated to have an 80% growth advantage over the previous BA.1 Omicron which became dominant in December.

The report also shows that 10% of Covid cases in the most recent week were reinfections in individuals who previously tested positive 90 or more days ago.

Omicron is more likely to cause reinfections compared to previous variants because its mutations enable it to break through immune defences acquired as a result of previous natural infections.

Reinfections are classed as cases occurring 90 days after a previous positive test

It is also more likely to evade protection from vaccines and cause infection in people immunised against Covid.

Waning immunity has been blamed for the rise in infections and hospitalisations among the over 75s in particular, most of whom received boosters four to six months ago.

Second boosters are being rolled out to adults in this age group in the community from next week, but will only be given once they are 24 weeks on from their last jag.

Elderly residents in care homes in Scotland began receiving their second boosters last week.

A data table published by PHS, from analysis by the UK Health Security Agency, illustrates how protection against hospitalisation wanes over time.

In the first three months after a booster, protection against hospitalisation is roughly 80-95% - meaning that 5-20% would still be at risk of hospitalisation.

By four to six months, however, protection wanes to around 75-85% - meaning that 15-25% of people in this group are at risk of hospitalisation.

That suggests that the increased risk of hospitalisation for over-75s now compared to Christmas - when most had been recently boosted - ranges from an extra 25% to as much as three times the risk.

However, the UKHSA cautions that the estimates have "low confidence" currently since Omicron is still a relatively new variant.