Coronavirus kills around 1.23 per cent of all infected patients, according to a major study.
Scientists say 3.4million people in England may have been infected with Covid-19 according to a major study — ten-fold higher than the official UK tally.
Imperial College London experts have carried out a mass coronavirus surveillance study, involving more than 100,000 volunteers who used home testing kits to check for antibodies, which reveal if someone has previously been infected.
The programme suggested around six per cent of England’s population had already been infected with Covid-19 by July 13.
If this estimate was true, it suggests the coronavirus kills around 1.23 per cent of all cases — based on data suggesting around 42,000 people have died in England. By contrast, seasonal flu has a death rate of around 0.1 per cent.
The figure is twice as high as the World Health Organization’s most recent mortality rate estimate of 0.6 per cent. Antibody surveillance studies have produced wildly different results across the world, ranging from as low as 0.25 per cent to 1.4 per cent.
Department of Health data shows only 313,798 cases have been diagnosed since the outbreak began. But hundreds of thousands of infected Brits were not tested during the height of the crisis, either because of a lack of swabs or because they never had any of the tell-tale symptoms.
Counting how many people who have coronavirus antibodies is, therefore, the most accurate way of calculating how much of the population has already been infected.
But research has suggested that antibodies decline three months after infection — meaning only a fraction of true cases during the peak of the crisis in March and April may have been spotted.
And some people may never develop antibodies at all, so the true number of cases will always be a mystery.
The Imperial study is in line with estimates from other antibody surveillance studies, including one led by a team at Cambridge University.
Cambridge academics — who have been making forecasts based on an array of data — last week calculated around eight per cent of England has had the disease.
Imperial researchers tracked the spread of infection across England after the Covid-19 pandemic’s first peak.
Volunteers tested themselves for antibodies — substances stored by the immune system to remember how to fight off a specific virus — at home between June 20 and July 13.
People living in London were most likely to have been infected, along with those working in care homes and health care, people from black, Asian and other minority ethnic groups, and people living in larger households.
The programme suggested a total of 13 per cent of people living in London had Covid-19 antibodies, compared with less than three per cent in the South West of England.
People working in care homes (16 per cent) and health care (12 per cent) returned far higher results than people who were not key workers, at 5 per cent.
The study found 17 per cent of black volunteers had antibodies, the categories of Asian and ‘other’ ethnic minorities had 12 per cent each. The figure among white volunteers was only five per cent.
People aged from 18-34 showed the highest incidence of antibodies, at 8 per cent, while over-65s had the lowest rate at just 3 per cent.
Volunteers in the most deprived areas of the country were slightly more likely to have antibodies than those in the wealthiest areas, at 7 per cent compared with 5 per cent, while those in households of more than six or seven people (12 per cent and 13 per cent) were more likely to have had Covid-19 than those in single or two-person households (five per cent).
Smokers were slightly less likely to have antibodies than non-smokers – at 3 per cent compared with 5 per cent – while 32 per cent of people with antibodies had shown no symptoms, a figure which rose to 49 per cent of those aged older than 65.
One of the scientists behind the study said that the coronavirus outbreak in the UK appears to have been ‘widely dispersed’ from the start.
The first patient to die with Covid-19 in the UK was recorded on March 5, when it was thought there were only 90 cases in the UK.
Professor Helen Ward told BBC Breakfast: ‘What was interesting (about the study) is that we can tell from people who reported not only having a positive test, but we also asked about their symptoms so we can actually track for most people – the 70 per cent of people who reported symptoms – when they think they were infected.
‘And it did start in January, February, and actually it started right across the country, so you can’t say that it started in London and spread out.
‘Right from the beginning it was widely dispersed.’
Health Minister Edward Argar hailed the study as an important development in Britain’s fight against the coronavirus.
‘Large scale antibody surveillance studies are crucial to helping us understand how the virus has spread across the country and whether there are specific groups who are more vulnerable, as we continue our work to drive down the spread of the disease,’ Mr Argar said in a statement.
‘We don’t yet know that antibodies provide immunity to coronavirus, but the more information we can gather on this virus, and the easier we can make it for people to participate in these studies, the better equipped we will be to respond.
‘The British public have already played a massive part in helping to keep the country safe and I’d urge them to consider signing up to one of the many vital surveillance studies taking place over the coming months as part of our national testing effort.’
The study’s authors also cautioned there was still no firm evidence the presence of antibodies meant people could no be re-infected with the virus.
Professor Graham Cooke, the research professor of infectious diseases and research lead at Imperial, said: ‘Using the finger-prick tests suitable for large scale home testing has given us clearest insight yet into the spread of the virus in the country and who has been at greatest risk.
‘These data will have important implications as decisions to ease lockdown restrictions in England.’