New research suggests that one in every 10 Londoners has previously been infected with Covid-19, with levels of infection rising to nearly one in five in ethnic minorities in the capital.
A study of more than 20,000 people across the UK found that 7.1% of the population have been infected with Sars-Cov-2, one in every 14 Britons.
The major study to examine the extent of previous infection across measured antibodies among participants, therefore indicating past infection with the virus.
But rates of previous infection were found to vary significantly across different sectors of society, with just 4.4% of the population in the South West of England having a positive antibody test.
But one in 10 Londoners (10.4%) has previously been infected.
Researchers also said that for some groups, infection rates were significantly higher than the general population.
Shockingly, 18.4% of participants from ethnic minority groups who are aged under 30 and living in London have previously been infected.
People from more deprived backgrounds were also more likely to have had a previous infection of the virus, with 6.1% of the wealthiest showing a positive antibody result compared to 8.9% of the most deprived.
The rate of previous infection was higher among black (11.3%) and South Asian (9%) participants compared to white people (6.9%), according to the UK Biobank study.
It was also found that under 30s were more likely to have a previous infection than over 70s. with just 5.4% of participants over the age of 70, having positive antibody tests, compared to 10.8% of those under 30.
Researchers found no difference between men and women for previous infection rates.
Sir Patrick Vallance, the Government’s chief scientific adviser, said: “Understanding the rates of infection and the persistence of antibody levels will be helpful for managing the ongoing process of coming out of lockdown safely, as well as supporting the development of vaccines against Sars-CoV-2.”
The study saw blood antibody tests conducted on 20,200 people over the age of 18 – a combination of existing Biobank participants, their children and grandchildren.
Participants provided a finger prick blood sample – and they are continuing to provide samples going forwards as well as information about any symptoms as the study continues.
The samples were examined by scientists at Oxford University.
These are the first findings from the study, which will continue throughout the year.
UK Biobank principal investigator, Sir Rory Collins – BHF professor of medicine and epidemiology at Oxford University, said: “The extraordinary response to our request for volunteers allowed us to set up a large prospective study of Sars-CoV-2 antibody levels that is representative of the UK population.
“It is crucial that the participants continue to send blood samples every month, to enable us to monitor changes in the rates of infection as the UK comes out of lockdown and to understand the persistence of antibodies to the coronavirus as a measure of natural immunity.”