The latest data suggests more than half of England's population now has Covid-19 coronavirus antibodies.
However, the Office of National Statistics (ONS), says "it is important to draw the distinction between testing positive for antibodies and having immunity".
Nonetheless, England Health Secretary Matt Hancock shared the news on Twitter and described the data as "hugely promising".
"This is the effect of the vaccine measured in real life," said Mr Hancock. "The vaccine is saving lives across the country, so when it's your turn, get the jab."
The ONS said: "We’ve published our latest antibody and vaccine data for the UK. We estimate that 1 in 2 people or 54.7% of the population in England tested positive for Covid-19 antibodies in the week ending 14 March 2021.
"In Wales, an estimated 1 in 2 people, or 50.5% of the population tested positive for Covid-19 antibodies in the week ending 14 March 2021.
"In Northern Ireland, an estimated 1 in 2 people, or 49.3% of the population tested positive for Covid-19 antibodies in the week ending 14 March 2021.
"In Scotland, an estimated 2 in 5 people, or 42.6% of the population tested positive for Covid-19 antibodies in the week ending 14 March 2021."
"The data show a reduction in antibody positivity rates among older individuals during the most recent days in the period analysed; this is likely because of people in these prioritised age groups having received their first vaccine dose but not yet their second dose; this does not necessarily mean they have no immunity protection against coronavirus (COVID-19).
"For the first time, we have included modelled estimates of the number of people who have received at least one dose of a vaccine; across all four countries of the UK there is a clear pattern between vaccination and testing positive for COVID-19 antibodies.
"It is important to draw the distinction between testing positive for antibodies and having immunity.
"Following infection or vaccination, antibody levels can vary and sometimes increase but are still below the level identified as 'positive' in our test, and other tests.
"This does not mean that a person has no protection against coronavirus (COVID-19) since an immune response does not rely on the presence of antibodies alone.
"We also do not yet know exactly how much antibodies need to rise to give protection. A person's "T cell" response will prvide protection is not detected by blood tests for antibodies."
