Researchers also said people deemed at moderate risk from the virus due to health conditions like diabetes 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, led by the University of Glasgow and published in the journal Scientific Reports, also showed that people aged 70 and over accounted for almost half (49.55%) of deaths in a Scottish health board.
The research – Comparison of Covid-19 outcomes among shielded and non-shielded populations – looked at patients advised to self-isolate for an extended period in NHS Greater Glasgow and Clyde (NHSGGC) between March and May last year.
The study looked at data from more than 1.3 million patients registered with GP practices in NHSGGC, of which 27,747 had been advised to shield, with a further 353,085 classed as medium risk due to health conditions.
The authors found that, compared with the remaining 934,239 people classed as low risk, people advised to shield were eight times more likely to get infected and five times more likely to die after confirmed infection.
Professor Jill Pell, director of the University of Glasgow’s Institute of Health and Wellbeing, said: “Our study highlights that to effectively protect high-risk individuals, shielding should be used alongside other population-wide measures such as physical distancing, face coverings and hand hygiene.
“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.”
In the shielded group, there were 299 (1.1 per cent) confirmed infections and 140 (0.51 per cent) deaths.
In the moderate-risk group, there were 1,859 (0.53 per cent) confirmed infections and 803 (0.23 per cent) deaths, and in the low-risk group, there were 1,190 (0.13 per cent) confirmed infections and 84 (0.01 per cent) deaths, researchers said.