More than eight in 10 adults in most parts of the UK are now likely to have Covid-19 antibodies, new figures suggest.
The estimates range from 85.4% of adults in Northern Ireland to 86.6% in England and 88.7% in Wales.
In Scotland the estimate is slightly lower, at just under eight in 10 adults, or 79.1%.
The presence of coronavirus antibodies suggests someone has had the infection in the past or has been vaccinated.
It takes between two and three weeks after infection or vaccination for the body to make enough antibodies to fight the virus.
Antibodies then remain in the blood at low levels, although these levels can decline over time to the point that tests can no longer detect them.
The latest estimates are from the Office for National Statistics (ONS) and are based on a sample of blood test results for the week beginning June 7.
The estimates are for people in private households and do not include settings such as hospitals and care homes.
In England, the latest estimate of 86.6% adults is up from 76.4% a month ago, while in Wales the estimate of 88.7% is up from 76.7%.
For Scotland the estimate is up month on month from 67.5% to 79.1%, and for Northern Ireland it is up from 74.2% to 85.4%.
The ONS said there is a clear pattern between vaccination and testing positive for Covid-19 antibodies but the detection of antibodies alone is not a precise measure of the immunity protection given by vaccination.
Once infected or vaccinated, the length of time antibodies remain at detectable levels in the blood is not fully known.
It is also not yet known how having detectable antibodies, now or at some time in the past, affects the chance of getting Covid-19 again.
The estimated percentage of adults testing positive for antibodies has continued to increase across all regions of England.
For the week beginning June 7, the estimates range from 82.2% in south-west England to 86.8% in north-west England.
Across England as a whole, the highest percentage of adults testing positive for Covid-19 antibodies was estimated to be the 65 to 69 age group (97.4%), followed by people aged 70 to 74 (97.3%) and 75 to 79 (96.8%).
The lowest percentage was for 16 to 24-year-olds (55.9%).
In Wales, the highest proportion of adults likely to have tested positive for antibodies was the 70 to 74 age group (98.4%) followed by 65 to 69 (98.0%), while in Scotland the highest percentage was for people aged 65 to 69 (97.3%) followed by 70 to 74-year-olds (96.3%).
In Northern Ireland, the ONS uses different age groups due to small sample sizes, and estimates that 95.7% of people aged 70 and over were likely to have tested positive for antibodies in the week beginning June 7.