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Coronavirus kills 1.04% of people who catch it, says new study

The coronavirus could kill 1.04 per cent of all people who catch it, according to scientists.

This death rate, estimated by researchers at Stanford University in California, would make COVID-19 10 times as deadly as the flu.

It could also mean that around 4.65million people in the UK have had the virus already, based on an estimated 48,417 people having died of the disease so far. 

Scientists have been unable to work out how deadly the virus really is because to do so you need to know the true number of people who have had it.

But many COVID-19 patients around the world are not being diagnosed either because their symptoms are so mild that they don’t realise they’re ill, or they don’t fit the criteria for government testing.

The Stanford team’s estimate sits at the top of the range of various calculations which have emerged in recent scientific papers, ranging from 0.1 – the same as the flu – to now 1.04 per cent.

If true, the figure would mean the disease kills one in every 100 people who catches it.

A death rate of 1.04 per cent could mean 4.65million people in the UK have had the coronavirus already – significantly fewer than other death rate models from past studies have suggested

The researchers estimated the death rate of the virus using a complex algorithm based on the number of people testing positive in 139 countries around the world.

They combined this with how accurate the tests were thought to be to create what they described as ‘a novel statistical approach based on sampling effort’.

It looked at how each country was deciding who to test, how many of their tests were positive, and took into account numbers of false negatives.

Running the numbers through their formula the researchers – Richard Grewelle and Giulio De Leo – put the global estimated infection fatality rate of the virus at 1.04 per cent.

It was somewhere between 0.77 per cent and 1.38 per cent, they said, with 1.04 their accepted mid-point. 

The paper was published on the website MedRxiv without being reviewed by other scientists to check for errors.


Up to 222,000 people in England may be infected with the coronavirus right now, according to a government testing survey which was published for the first time last week.

The first round of random public testing identified only 33 positive cases of COVID-19 out of a sample of 10,705 people and estimated a national infection level of 0.27 per cent – one in every 370 people.

Professor Jonathan Van-Tam, deputy chief medical officer for England, said at a Downing Street briefing that the data represented ‘really quite a low level of infection’ in the community.

This suggests that 148,000 people had the virus at any given time between April 27 and May 10, that figure being the middle estimate between a low of 94,000 and high of 222,000. During that time 66,343 people were officially diagnosed.

And the rate of infection is six times higher in healthcare workers and carers than it is in the general population, the survey found. 

While 1.33 per cent of people who worked in patient-facing roles in hospitals or homes tested positive for the virus, only 0.22 per cent of those with other jobs did so.

Numbers announced did not include anyone who was tested in a care home or a hospital, where the statisticians said ‘rates of COVID-19 infection are likely to be higher’.

Most official testing, which has picked up around 250,000 positive cases over the entire outbreak, is being done in hospitals and care homes.  

The Office for National Statistics is soon expected to publish antibody data showing how many people have had the infection already but does not currently have enough data for a reliable estimate.

The current survey, of which this is the first set of data, will be ongoing as part of the government’s ‘test, track and trace’ plan for getting out of lockdown and will be expanded to regular testing in more than 10,000 households.

‘Our estimated IFR [infection fatality rate] aligns with many previous estimates and is the first attempt at a global estimate of COVID-19 IFR,’ the scientists said.

The difficulty of estimating a global fatality rate, they said, is made greater by differences in testing strategies across countries, as well as factors which make some populations more or less at risk of severe disease.

The researchers added: ‘The estimate of IFR in one locality will differ from the IFR in another due to differences in underlying health conditions, demography, and medical treatment.

‘Rather than understanding the extent of the variability these factors can create in IFR measurements, we derive a new approach to IFR estimation using global data.

‘Provided testing has prioritized people at highest risk of SARS-CoV-2 infection, the metric of relative testing capacity used in our approach should reflect each country’s ability to accurately estimate the true IFR.’

Understanding how deadly the virus is can reveal the true number of people who have been infected with the disease through reverse engineering.

For example, if the fatality rate is 1.04 per cent, it means 10.4 die out of every 1,000 who are diagnosed.

Statistics suggest that the true death toll in Britain is currently around 48,417. 

Figures from Office for National Statistics, National Records Scotland and NISRA, the Northern Ireland statistics agency, suggest that the true number of people who have died of COVID-19 is 37 per cent higher than the Department of Health has counted.

By May 8 those organisations had recorded 42,862 deaths, while the Department of Health had recorded 31,241 in comparison – a 37 per cent difference.

Applying the same increase to today’s death toll of 35,341 puts the current number of victims at 48,417. 

If 1.04 per cent is the true death rate the number of people who have died so far suggests that 4.65million people have been infected with the virus. 

Studies in other countries, based on surveys in other Western cities of whose blood tests showed that they have had the infection in the past, put the death rate between 0.19 and 0.79. 

If those are more accurate, the number of people who have had the infection in the UK varies wildly from a low of 4.65m to a staggering 48.4m, which would be expected if COVID-19 were similar to the flu.

Those calculations work out like this:

  • 0.1 per cent death rate (influenza): 48.4million cases in the UK 
  • 0.19 per cent death rate (as found in Helsinki, Finland): 25.48m 
  • 0.37 per cent death rate (Gangelt, Germany): 13.08m
  • 0.4 per cent (Stockholm, Sweden): 12.1m
  • 0.79 per cent (New York, US): 6.12m
  • 1.04 per cent (Stanford study): 4.65m