The number of people who have antibodies for the virus which causes Covid-19 has increased across the UK, according to data from the Office for National Statistics.

In England, an estimated 1 in 5 people would have tested positive for antibodies against SARS-CoV-2 on a blood test in the 28 days up to 1 February 2021.

This suggests they had the infection in the past or have been vaccinated.

It compares to one in seven in Wales and Northern Ireland and an estimated one in nine in Scotland.

Having antibodies in the blood indicates that people have either previously been infected with the virus or have had a Covid-19 vaccine.

The analysis is based on blood test results taken from a randomly selected subsample of individuals aged 16 years and over, which are used to test for antibodies against SARS-CoV-2.

This can be used to identify individuals who have had the infection in the past or have developed antibodies as a result of vaccination.

It takes between two and three weeks after infection or vaccination for the body to make enough antibodies to fight the infection.

Antibodies remain in the blood at low levels, although these levels can decline over time to the point that tests can no longer detect them. Having antibodies can help to prevent individuals from getting the same infection again.

Measuring the presence of antibodies understands who has had coronavirus (COVID-19) in the past and the impact of vaccinations. Once infected or vaccinated, the length of time antibodies remain at detectable levels in the blood is not fully known.

Older people were more likely to have antibodies in England, but in Scotland, Wales and Northern Ireland the highest rates were seen among younger adults.

The highest percentages of people testing positive for antibodies were those aged 80 years and over in England, those aged 16 to 24 years in Wales and Scotland, and those aged 25 to 34 years in Northern Ireland, in the 28 days up to 1 February 2021.

Esther Sutherland, principal statistician for the Covid-19 Infection Survey, said: “Antibody positivity rates have increased across all four nations and the effects of the vaccination programmes have begun to appear, especially in the older age groups.”