Mystery over spike in Covid deaths on hottest day of the year: Virus fatalities doubled in 40C heat
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Covid deaths spiked on the hottest day ever in what experts say could be the first sign of a surge in heatwave fatalities.
Official figures show 258 people with the virus died on July 19 in England — the same day the mercury hit 40.2C (104.4F).
The figure was up by 100 (68 per cent) in a week and marks the highest daily fatality toll since April, when infections were at record levels.
However, deaths are still running at a fraction of the levels seen during the darkest days of the pandemic.
Scientists trying to unpick the sudden spike say Covid infections were already at very high levels when the heatwave hit.
They suggest the rise in deaths may have been among people who died from heat-related illnesses but happened to have Covid at the same time.
Others warned some elderly and vulnerable people may have died because they were isolating alone with the virus. The sweltering temperatures may have also worsened people’s Covid infections.
However, the way deaths are registered in the NHS mean many of the deaths likely occurred days before they were actually posted on the Government dashboard.
Daily virus deaths had already been rising slowly earlier this month and an estimated 3.1million people were infected in the days leading up to July 19.
A Met Office graphic last week shows how parts of London and southern England suffered record temperatures of up to 40C
Heatwaves kill up to 2,000 Britons every summer, as dehydration and heatstroke can lead to deadly blood clots, strokes and cause deterioration among those already suffering underlying conditions.
Accidents and injuries, such as from car crashes, are also more common during hot spells.
While the true death count linked to two days of record-breaking heat last week won’t be known for months, experts estimate more than 800 people died across the UK last Monday and Tuesday alone.
The Covid data, published by the UK Health Security Agency, counts all virus deaths among Britons who tested positive in the previous 28 days.
However, not all of these deaths are primarily caused by the virus.
Separate data shows that Covid is the underlying cause in only six in 10 deaths posted to the Government dashboard.
Scientists trying to unpick the sudden spike told MailOnline Covid infections were already at very high levels when the heatwave hit an estimated 3.1million people were infected in the days leading up to July 19. Experts suggest the rise may have been among people who died from heat-related illnesses but happened to have Covid at the same time
This graph shows the number of deaths directly due to Covid recorded in England and Wales. The number of deaths being recorded these nations currently is far below that of previous waves earlier year and a sheer fraction of those seen at the start of 2021
A Covid infection can also worsen the condition of those already unwell, especially heart and breathing problem sufferers.
The two days of data available since the spike last week show that daily deaths dramatically fell by 57 per cent within 48 hours. Meanwhile, hospitalisations have been falling for two weeks.
Meaghan Kall, an epidemiologist at the UK Health Security Agency, said it is too soon to know for certain what caused the spike.
But high prevalence of the virus — with one in 17 people in England thought to be infected at the time — coupled with the heatwave, could be to blame.
‘The curious question is what fraction is excess heatwave deaths, versus Covid, or potentially a combination of the two with the heat exacerbating severe Covid disease,’ she wrote on Twitter.
Hot weather can cause dehydration, which causes blood to thicken. It also lowers blood pressure, making it harder to push blood around the body. This can lead to blood clots and strokes.
And overheating can make symptoms worse for those with heart and breathing problems — which can become fatal.
There is also a higher risk of heat exhaustion and heat stroke, especially if exercising outdoors when it’s hot. This is caused by not drinking enough and losing fluids through sweat.
Older people, those living on their own or in care home and sufferers of long-term conditions are the most at risk.
Those confined to bed, with pre-existing conditions such as respiratory disease and heart problems are most at risk.
Professor Paul Hunter, an infectious disease expert based at the University of East Anglia, told MailOnline that heatwaves can kill ‘sometimes sadly in very large numbers’.
Some of the increase in Covid deaths ‘will have nothing to do with’ being infected with Covid, while other fatalities will be among infected people who ‘without the heatwave, would have survived’, he said.
Professor Hunter added: ‘Some may have died because the fact that they had Covid meant that they were more socially isolated than usual and so at greater risk from the heatwave.
‘All of these factors probably play a role and we may never know for certain, how many of these excess deaths were due to each of these reasons.’
Professor Lawrence Young, a virologist at the University of Warwick, told MailOnline that the heatwave could have ‘exacerbated the effects of Covid infection’.
However, he said it is ‘always difficult to disentangle data on deaths’ due to how it is collected.
Professor Yong said: ‘This spike of Covid deaths is an obvious reflection of the very high levels of infection we have been experiencing over recent weeks.
‘It’s been estimated that around 70 per cent of these deaths are not directly due to Covid but are recorded as incidental infections as people are being tested on admission to hospital.
‘It could be that the heatwave exacerbated the effects of covid infection, particularly in people with underlying health conditions.’
However, Dr David Strain, a senior clinical lecturer at the University of Exeter, told MailOnline that the high death count is ‘unlikely to be directly attributable to the hottest day of the year’.
The day a death is registered usually ‘reflects the activities of the previous two or three days rather than what was going on on that particular day’, he said.
So the fatalities registered on Tuesday July 19 ‘are likely to be the ones occurring over the weekend’, he said.
Dr Strain added: ‘I suspect that this is just a representation of the impact of the BA.5 variant which we know is returning to the lungs in a similar way to the Delta variant was and moving away from the upper airways where BA.2 was mostly active.’
He said despite nine in 10 people in the UK bein double-jabbed, which reduces the risk of severe disease and death from Covid, it is not enough to ‘prevent peaks like this from occurring’.
Covid cases, hospitalisations and deaths are set to fall in the coming weeks, but ‘until that happens we are back to the same old story of make sure that your vaccines are up-to-date because that is the best way to protect yourself’, Dr Strain added.