More than 3.4 million people in England have developed antibodies to the coronavirus, corresponding to almost 6% of the population - a higher proportion than previously thought.
The findings, released on Thursday, suggest that at the end of June, some 13% of Londoners had antibodies, more than twice the national average. The people least likely to show antibodies were in south-west England, with a rate of only 3%.
While there are many "unknowns" related to the coronavirus, "these data will have important implications for decisions around ongoing control measures in England," said Graham Cooke, NIHR Research Professor of Infectious Diseases and research lead at Imperial College London.
About 100,000 people took part in England's first nationwide antibody surveillance study using self-testing kits at home.
Participants used a finger-prick test to draw a drop of blood, read the result and then uploaded it online.
The study showed members of ethnic minorities were between two and three times more likely to have had Covid-19 than white people.
Health and home-care workers
Other findings suggested that health care workers were most likely to have had the virus.
More than 16% care-home workers who had contact with patients had antibodies, the study found.
Young adults between the ages of 18 and 24 were more than twice as likely to have antibodies (8%) compared to older people aged between 65 and 74 (3%).
The study was conducted between June 20 and July 13, and led by Imperial College London. The initial report, which has not yet been peer reviewed, was first published by medRxiv, a medical news website.
