One in 15 people living in London may already be infected with a coronavirus, according to a study by some scientific advisers to the British government, but only 9,291 cases have been confirmed in the capital – a gap which highlights the lack of screening services in the largest cluster country.
Researchers from the Covid-19 response team at Imperial College London, whose previous work contributed to the decision to lock down the UK last month, estimated in an article this week that between 1 , 2% and 5.4% of the country’s population may have already been infected. before March 28.
Based on the average of 2.7%, this would imply that one in 15 people, or about 600,000 people, in the capital have contracted the virus, adjusting for the Greater London population of 8.9 million. locals and the fact that it has about a third of all confirmed cases. So far, the city has suffered a similar proportion of all deaths in the UK.
However, the range of the study could mean up to one in eight Londoners has been infected or only one in 33, according to calculations by the Financial Times which were reviewed by one of the document’s authors.
The government’s policy of testing only critically ill patients and those in localized places, such as nursing homes, has come under increasing criticism. This is in stark contrast to the recommendation of Tedros Adhanom, the head of the World Health Organization, to “test, test, test”.
The government has also been criticized for failing to test more front-line National Health Service workers after admitting earlier this week that only 2,000 out of 500,000 had been tested.
Ministers have repeatedly promised to increase testing, but progress has so far been slow. Many scientists argue that large-scale, targeted testing is essential to stem the spread of the virus, as many infected people have no symptoms or are very mild and continue to spread it to others.
The document, which has been submitted for peer review, is among the first to estimate totals, including asymptomatic and mild cases, creating a model for “recalculating” a range of totals from the number of deaths observed.
“We estimate that there are orders of magnitude fewer infections detected than real infections, mainly due to mild and asymptomatic infections as well as limited testing capacity,” said the newspaper, published on 30 March.
But the study warns that the data on which the team’s estimates are based is still relatively limited, given the rapid rate of spread of the virus since its appearance in Wuhan, China, at the end of the last year. There is usually a lag of about four weeks between infection and death for the relatively small percentage of people who succumb to the virus.
The document, which examined 11 European countries, argues that transcontinental bans have already saved between 21,000 and 120,000 lives.
“It is too early to say whether we have successfully brought the epidemics under control and that more difficult decisions will have to be made in the coming weeks,” said Dr. Samir Bhatt, infectious disease epidemiologist at the School of Public Health. from Imperial College and lead author. On paper.
The British government’s decision to lock down last month was partly influenced by fears about the rapid spread of the virus in London.
London’s relatively high infection rate suggests that further measures may be necessary. Although traffic on public transport has fallen sharply, complaints about crowded underground trains during rush hour after the reduction of Transport for London services persist.
Scientists have said that antibody tests will be essential to determine the real rates of infection. “The impact of the pandemic is extreme – but it would have been much worse without the interventions,” said Professor Axel Gandy, another of the document’s authors. This is a view supported by many other scientists who follow the virus.
Tim Colbourn, epidemiologist at the Institute for Global Health at University College London, said that the spread rate in London suggested by the Imperial newspaper “seems plausible, with the available data.”
“But we are still far from collective immunity and it is unlikely to be for months at best. The only way out of the lockout is to conduct massively extensive testing and contact tracing, ideally at a much more local level. I agree that there are many more infected than the tests show, because we have not done community tests for weeks and this was spreading a lot, especially before the lock-out, “he said. -he declares.
A study carried out last week by the University of Oxford estimated an even higher infection rate, but has been criticized by parts of the scientific community for being too speculative.
When the high number of cases estimated in London based on the Imperial College study is removed, this suggests a lower percentage of infections outside the capital, although epidemiologists have stated that this could change rapidly. in the coming weeks.
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FT calculations based on Imperial’s average estimate imply that about 1 in 50 people outside London were infected as of March 28, although it is still more than 1.2 million people.
At the upper end of the estimated range, with 5.4% of the total population, it could already be one in 24 people outside of London.
The college’s earlier study suggested that the UK would have killed up to 250,000 people if the government had continued its more relaxed approach to social distancing and isolation, which stopped long before a complete foreclosure until ‘at the end of March.
Jim Pickard’s additional report in London