Coronavirus has increased the chances of people dying proportionately across the population, regardless of underlying health issues, a new study has suggested.

However, this increase has had the biggest impact on the numbers of people with pre-existing health conditions dying, because they were already at greater risk.

Using GP data, researchers estimated excess deaths in the UK during the first wave of the pandemic – between March 5 and May 27 last year – in nearly 10 million adults aged 40 and over.

They compared these to pre-pandemic death rates from any cause in people with differing health and socio-economic profiles.

According to the data, on average the rate of death during the wave increased by just over 40% compared to before the pandemic.

The increase in death rate was largely consistent across the population, regardless of people’s health conditions and other characteristics, researchers found.

Our work has shown that the threat posed by Covid-19 increases evenly with frailty or ill health caused by aging and a wide range of respiratory and non-respiratory medical conditions

However, the researchers highlight that before the pandemic people with pre-existing health conditions such as heart disease or asthma had a higher mortality rate than people without these conditions.

Therefore, increasing their chances of dying by a further 40% had a bigger absolute impact on them, compared with healthy individuals.

Professor Sir David Spiegelhalter, chairman of the Winton Centre for Risk and Evidence Communication, University of Cambridge, said: “It’s good to have confirmation that the risks from Covid have been roughly proportional to the individual risks we all face in life – it serves to exaggerate any weaknesses we have.

“As the authors say, even if we all have a similar relative risk, the vulnerable start from a higher baseline and so have had a higher absolute risk of dying.

“For reasons that are not entirely clear, this virus picks on the weak and vulnerable. It is a bully.”

However, the study found some exceptions.

The death rates of those with dementia and learning difficulties were disproportionately affected by the pandemic.

Both groups had around three times the rate of death compared to people without the condition before the pandemic.

However, this was approximately five times the rate of death compared to people without the condition during the first wave of the pandemic.

Looking at ethnicity, the researchers found that before the pandemic black people had a 20% reduced rate of death compared to white people, but there was a 50% increase during wave one.

Those living in London also had a lower rate of death before the pandemic compared to people living outside of London, but this rose substantially during the first wave.

Dr Helen Strongman from the London School of Hygiene & Tropical Medicine (LSHTM), who co-led the research, said: “Our work has shown that the threat posed by Covid-19 increases evenly with frailty or ill health caused by aging and a wide range of respiratory and non-respiratory medical conditions.

“This compares to flu, which also tends to be more dangerous in the elderly but also affects young children and is more strongly associated with respiratory conditions such as asthma, COPD (chronic obstructive pulmonary disease) and smoking.”

She added: “Our study shows that Sars-CoV is a predatory virus, amplifying mortality rates across the board, and having the biggest impact on those with existing ill health or who are frail.

“This emphasises how important it is for everyone to protect themselves and the most vulnerable in society through measures such as vaccination and wearing face masks.

“However, more basic research about why and how the virus exploits any vulnerability is needed.”

The authors say further research is needed to clarify whether there were differences across waves in the UK, and acknowledge limitations of the study.

This includes the potential for misclassification of the date of death for a small number of individuals and the misclassification of health factors through incomplete information.

Conducted in partnership with UCL, the study is published in PLOS Medicine.