More than two-thirds of adults in private households in England are likely to have antibodies against Covid-19, a survey by the Office for National Statistics (ONS) reveals.
About 68.3% of adults living in homes - which excludes those in care homes, hospitals and other institutional settings - have either had the coronavirus vaccine or have previously contracted the virus, as of the week ending April 11.
This is up from the estimate of 53.1% two weeks earlier.
The presence of Covid-19 antibodies suggests someone has had the infection in the past or has been vaccinated.
The North West of England had the highest estimated percentage of antibody positivity - 69.9%. Meanwhile, the North East had the lowest - 64.4%.
In Wales, it is estimated that 61% of adults living in homes have antibodies. This is up from 48.2% two weeks earlier.
An estimated six in 10 adults in private households (62.5%) had antibodies in Northern Ireland. Two weeks ago, the estimate was 54.6%.
And in Scotland, about 57.8% of adults are thought to be protected from Covid-19 in the week ending April 11 - up from 43.8%.
Coronavirus: What you need to know - Listen in for the latest information, advice and analysis on the pandemic
It comes as the UK reached a new vaccine milestone by fully inoculating a quarter of its adult population.
The ONS said there is a "clear pattern" between vaccination and the presence of antibodies, but clarified the detection of antibodies does not necessarily mean people have enough of it to be immune from Covid-19.
Adults aged 70 to 74 had the highest proportion with antibodies was 70-74. In the week ending April 11, it is estimated that 87.6% had some protection.
In early to mid-March 2021, the ONS reported a fall in the estimated proportion of older adults with antibodies. But the proportion has since risen again, likely reflecting the increase in the number of people receiving their second vaccine dose.
Sarah Crofts, senior statistician for the ONS' Covid-19 Infection survey said: “Our data today show an increase in antibody levels across all four UK nations – reflecting the growing success of the vaccine rollout.
“In England, we estimate 7 in 10 adults would now test positive for antibodies against COVID-19. These kind of antibody levels are really encouraging as we transition out of lockdown.
“Those in their early 70s are the group with the most people testing positive for antibodies – likely due to that age group now having received the second dose of the vaccine.”
More than 33 million UK adults (64.3%) have received their first vaccine dose, as of the end of Monday. And more than 13 million people (25.1%) have been fully vaccinated.