Analysis by the Office for National Statistics (ONS) found that if the country’s entire population was tested, around 1 in 17 people would show positive results for Covid-19 antibodies.
The ONS data comes just a day after researchers said antibody testing may be underestimating the number of people previously infected by the virus.
In an article published in the British Medical Journal (BMJ), scientists said large-scale surveys may not capture all the people who have developed an immune response to the disease.
In its own study published on Friday, the ONS said that six per cent of individuals aged over 16 had shown antibodies when blood samples were tested.
This suggests 2.7 million people in England have developed some degree of Covid-19 immunity.
However, it said there was evidence of regional differences in the percentage of people testing positive for antibodies.
In London, an estimated 11 per cent of people have tested positive for antibodies – the highest for any region in England.
The lowest regional estimate was 3.5 per cent for south-west England.
The estimates refer to people in private households and are subject to revision, the ONS said.
It comes after British scientists suggested major seroprevalence surveys may not offer an accurate indication of immunity levels.
Seroprevalence surveys estimate the proportion of the population that have previously been infected with a virus by measuring the presence of antibodies produced.
The team of researchers, from the University of Cambridge, University Hospital Wales, and St George’s, University of London and St George’s Hospital, said these are important for calculating hospitalisation and fatality rates.
They said in their report, published in the BMJ on Thursday, that large-scale UK seroprevalence surveys have generally provided “low estimates of virus spread”, suggesting that 15 per cent of people in London and only four per cent of people in the south-west and south-east of England have been exposed to the virus.
But they said more thorough forms of antibody testing – conducted in Luxembourg and Austria – offered up to five times as many positive results.
Such tests measure antibody classes in the bloodstream as well as in mucus, respiratory and digestive tracts, and fluid around the eye.
Dipender Gill, a clinician at St George’s, University of London and St George’s Hospital, said: “Current seroprevalence surveys may be dramatically under-estimating the proportion of people that have been infected by the virus.
“Further work is required to determine the optimal survey strategy and appropriately revise these figures.”
Researchers said that timing could also be an issue because testing too early could mean an immune response might not have developed but testing too late could mean the immune response has diminished.
Mark Ponsford, a clinical immunologist at the University Hospital of Wales, said: “The immune response to the virus is more complex than a simple ’yes ’ or ’no’ to the presence of a single antibody type in the blood.
“It’s important that future surveys take this into account, and that we begin to standardise our approach to testing.
“This will help us to improve accuracy and allow more valid comparisons of the results from different surveys.”