People advised to shield during the first wave of the pandemic were eight times more likely to get Covid-19 and five times as likely to die following infection than the general population, a study has indicated.

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%) confirmed infections and 140 (0.51%) deaths.

In the moderate-risk group, there were 1,859 (0.53%) confirmed infections and 803 (0.23%) deaths, and in the low-risk group, there were 1,190 (0.13%) confirmed infections and 84 (0.01%) deaths, researchers said.

A Scottish Government spokesman said: “While we are no longer asking people to shield in the same highly restrictive way we did during the first wave of the pandemic, 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.

“As Scotland has progressed to Level 0, it is now safe for those at the highest risk to follow the same guidance as the rest of the population due to the success of the vaccination programme.”