This summer’s heatwaves were the deadliest in recent years, amid fears that coronavirus and lockdowns may have contributed to the death toll. 

Excess deaths during three significant heatwaves in June and August contributed to 2,556 deaths, up from less than 1,000 in recent years, Public Health England estimated. Deaths from Covid-19 were not counted.

Experts said the prolonged nature of the heatwaves, with each lasting for several days, coupled with the fact that many elderly people were spending significant amounts of time at home or in isolation could have amplified the death toll, which was the worst in 15 years. 

In June Public Health England warned that people recovering from Covid-19 at home, and those who were socially isolated or in a care home might be particularly at risk from high heat. 

Releasing the figures on Thursday it said more work was needed to examine how Covid and heat combined to create dangerous conditions. 

"The severity and intensity of the heatwave alone does not fully explain the magnitude of the impacts observed," the report said.

 Elderly and vulnerable people are particularly at risk from heat-related death, particularly if they have preexisting cardiovascular or respiratory conditions.

Maarten van Aalst, director of the Red Cross Red Crescent Climate Centre, said that factors such as people being afraid of going out in search of cooler spaces, community help being less available and measures such as public water fountains being cordoned off could be relevant, but it was too soon to say for certain how impactful this was.

High heat-related death rates were seen across Europe, including in places where Covid incidence was low, he said, adding that continuous high heat made it harder for people to recover. 

The largest spike in deaths was between August 5 and 15, after the end of lockdown and coinciding with the longest heatwave, suggesting that impact from Covid-19 would have been because of vulnerable people shielding. 

August heatwave in UK, in pictures

Bob Ward, policy and communications director at the Grantham Research Institute on Climate Change and the Environment at the London School of Economics and Political Science said that behavioural change due to Covid might have exacerbated the death toll. 

"We do know that those people who are particularly vulnerable to the effects of heat are largely the same people who are most at risk for Covid.

"The level of deaths that Public Health England have announced today are much bigger than we’ve seen in the past, which suggests that whatever impact the virus had, it only made things worse," he said. 

Dr Friederike Otto, acting director of the Environmental Change Institute, University of Oxford said his research showed that climate change had made dangerous heat waves more likely.

"Heat waves are by far the most deadly impact of climate change, and they are occurring today, not in a far future," he said.