In England, an estimated 1 in 2 people, or 54.7% of the population (95% credible interval: 49.3% to 60.5%) would have tested positive for antibodies against the coronavirus – SARS-CoV-2 – on a blood test in the week ending 14 March 2021, suggesting they had the infection in the past or have been vaccinated.
In Wales, an estimated 1 in 2 people, or 50.5% of the population (95% credible interval: 44.2% to 57.2%) would have tested positive for antibodies against SARS-CoV-2 on a blood test in the week ending 14 March 2021, suggesting they had the infection in the past or have been vaccinated.
In Northern Ireland, an estimated 1 in 2 people, or 49.3% of the population (95% credible interval: 41.8% to 59.7%) would have tested positive for antibodies against SARS-CoV-2 on a blood test in the week ending 14 March 2021, suggesting they had the infection in the past or have been vaccinated.
In Scotland, an estimated 2 in 5 people, or 42.6% of the population (95% credible interval: 37.1% to 48.6%) would have tested positive for antibodies against SARS-CoV-2 on a blood test in the week ending 14 March 2021, suggesting they had the infection in the past or have been vaccinated.
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 provide protection but is not detected by blood tests for antibodies.
