SCOTLAND’s Covid shielding strategy had limited effect in preventing infections and deaths amongst those at highest risk as it did not cover enough vulnerable groups, a major new study has revealed.

Research involving more than one million patients shows those advised to isolate were eight times more likely to contract the virus, 18 times more likely to be hospitalised and five times more likely to die than low risk people.

People with specific cancers, organ donor recipients and pregnant women with significant heart disease were among those deemed extremely clinically vulnerable to Covid.

However, the study, which was led by The University of Glasgow, found that three quarters of deaths were among those with conditions including diabetes and high blood pressure who were classed as at moderate-risk and had not been advised to shield. 

In the shielded group, there were 299 confirmed infections and 140 deaths while in the moderate risk group, there were 1,859 infections and 803 deaths.

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Older people over the age of 70 accounted for 49.55% of deaths and they were 78 times more likely to die, which the authors said provided an argument for including them on the shielding list.

Researchers said more than one-quarter of the general population would have needed to be effectively shielded to prevent over 80% of deaths. 

Shielding was recommended but not monitored or enforced in the UK.

Forty one percent of people advised to shield in Scotland reported stringently following  guidance and 21% reported they were unable to comply for a variety of reasons such as supporting other household members, caring for pets, avoiding domestic abuse, or undertaking essential chores.

Public Health expert, Professor Linda Bauld OBE, said the study provided useful evidence for future public health messaging aimed at protecting vulnerable people.

A spokesman for the Scottish Government said it was confident that shielding had helped protect those most at risk from Covid and said the study was limited to one geographical area and did not take into account ethnicity, rurality, exposure to health and social care workers, and compliance with restrictions.

Out of 1.3million people, 27,747 individuals were advised to shield  and a further 353,085 individuals had not been advised to shield but were categorised by the researchers as at medium risk of Covid-19.

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In the low-risk group, there were 1,190 (0.13% confirmed infections) and 84 (0.01%) deaths from Covid-19.

Moderate-risk individuals were four times more likely to have confirmed infections than the low-risk group, and five times more likely to die following confirmed infection.

The study found the effectiveness of shielding may be different in countries with different levels of support, monitoring or compliance and said in order to be effective “shielding criteria would have needed to be widely expanded to include other criteria, such as the elderly”.

Professor Jill Pell, Director of the University of Glasgow’s Institute of Health and Wellbeing, said:“Our study also showed that shielding may be of limited value in reducing burden on health services because, in spite of the shielding strategy, high risk individuals were at increased risk of death.

“We believe that, to be effective as a population strategy, shielding criteria would have needed to be widely expanded to include other criteria, such as the elderly.”

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Linda Bauld, a Professor of public health at Edinburgh University, said: “One clear finding from this paper is that shielding cannot completely protect vulnerable individuals in the face of a highly infectious virus.

"When it is present in the community, it’s not possible to completely cut off this group from interacting with others for essential reasons (care at home, obtaining essential supplies etc) and this study illustrates this. 

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“It also shows us how difficult it is to effectively use a shielding strategy and how many more people - over one quarter of the general population - would have to shield to prevent the vast majority of deaths. 

“Evidence such as this is useful as we plan ahead to be better prepared to address future epidemics or pandemics and also in terms of advice and support to those more vulnerable if we have outbreaks even localised in the coming months.”

A Scottish Government spokesman said: “We are confident the shielding programme helped vulnerable people who were at risk of COVID at that time. 

“This study is limited to one geographical area and doesn’t take into account a range of factors including ethnicity, rurality, exposure to health and social care workers, and compliance with restrictions.

"It also highlights that the findings are representative of Glasgow and Greater Clyde area but may be less so for other areas.”

The study, ‘Comparison of COVID-19 outcomes among shielded and non-shielded populations,’ is published in Scientific Reports.