Coronavirus (COVID-19) Infection Survey, antibody data, UK: 18 May 2022

In this bulletin, we report percentages of the population that are estimated to have antibodies against SARS-CoV-2, the specific virus that causes coronavirus (COVID-19).

In the week beginning 2 May 2022, the percentage of people estimated to have antibodies against SARS-CoV-2 at or above the antibody level of 179 nanograms per millilitre (ng/ml):

• in England, was 99.1% of adults (95% credible interval: 98.8% to 99.3%)

• in Wales, was 98.9% of adults (95% credible interval: 98.4% to 99.2%)

• in Northern Ireland, was 98.9% of adults (95% credible interval: 97.9% to 99.4%)

• in Scotland, was 99.1% of adults (95% credible interval: 98.7% to 99.3%)

• in England, was 95.5% of children aged 12 to 15 years, and 88.7% of children aged 8 to 11 years

About this bulletin

As the coronavirus pandemic and vaccinations have evolved, we have reviewed how we present information about antibody levels.

In our previous bulletin, Coronavirus (COVID-19) Infection Survey, antibody data, UK: 4 May 2022, we introduced an additional antibody series based on a higher level of 800 ng/ml. This week, these estimates are subject to additional quality assurance and so have not been updated. Antibody data for the 800 ng/ml level up to 17 April 2022 can be found in our Coronavirus (COVID-19) antibody data for the UK: dataset, for information.

Antibody estimates for those aged under 16 years in Wales, Northern Ireland and Scotland have also not been updated in this release as they are undergoing additional quality assurance.

Further information on antibody test levels, and the link between antibodies and infections can be found in our recent blog post Relationship between COVID-19 infections and antibodies: what do the data show?

In the week beginning 2 May 2022, the percentage of the adult population estimated to have antibodies against SARS-CoV-2 at or above the level of 179 nanograms per millilitre (ng/ml) remained high across the UK.

Antibody estimates for UK countries and regions in England can be found in our Coronavirus (COVID-19) antibody data for the UK: dataset.

Figure 1: The percentage of the population who are estimated to have antibodies against SARS-CoV-2 remained high across the UK in the week beginning 2 May 2022

Modelled percentage of the population with levels of antibodies against SARS-CoV-2 at or above 179 nanograms per millilitre (ng/ml), by age group, UK countries, 7 December 2020 to 5 May 2022

Notes:

1. All results are provisional and subject to revision.
2. These statistics refer to antibody tests for individuals living in private households.
3. In Northern Ireland, the number of people sampled is low compared with England, Wales and Scotland; therefore, adults aged 50 to 69 years are included in the same age group, and those aged 70 years and over are included in the same age group.
4. All estimates are subject to uncertainty, given that a sample is only part of the wider population. A credible interval gives an indication of the uncertainty of an estimate from data analysis.
5. The denominators used for antibodies are the total for each age group in the sample at that particular time point, then post-stratified by the mid-year population estimate.
6. Estimates for children aged 8 to 15 years are not available before 29 November 2021.
7. Estimates of antibodies at or above the 179 ng/ml level for children aged 8 to 15 years in Wales, Northern Ireland, and Scotland have not been produced for this release.

Download the data

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Antibodies

We measure the levels of antibodies in people who live in private households to understand who has had coronavirus (COVID-19) in the past and the impact of vaccinations. It takes between two and three weeks after infection or vaccination for the body to make enough antibodies to fight the infection. Antibodies can help prevent individuals from getting the same infection again. Once infected or vaccinated, antibodies remain in the blood at low levels and can decline over time.

SARS-CoV-2

This is the scientific name given to the specific virus that causes COVID-19.

Credible interval

A credible interval gives an indication of the uncertainty of an estimate from data analysis. A 95% credible interval is calculated so that there is a 95% probability of the true value lying in the interval.

Reference dates

The antibody estimates for the most recent week in this publication include data from 2 to 5 May 2022.

Our Coronavirus (COVID-19) Infection Survey methodology article provides further information around the survey design, how we process data, and how data are analysed. Our Quality and Methodology Information explains the strengths and limitations of the data, methods used, and data uses and users.

More information on measuring the data is available in the Coronavirus (COVID-19) Infection Survey statistical bulletin.

Survey data

The analysis on antibodies in this bulletin is based on blood test results taken from a randomly selected subsample of individuals aged 8 years and over who live in private households. The survey excludes those in hospitals, care homes and other communal establishments. The blood samples are used to test for antibodies against SARS-CoV-2.

Antibodies and immunity

Antibody positivity is defined by having a fixed concentration of antibodies in the blood. A negative test result occurs if there are no antibodies, or if antibody levels are too low to reach a level at the time of testing. It does not mean that their antibody level is at zero or that a person has no protection against COVID-19. Additionally, there are other parts of the immune system that will offer protection, for example, a person's T-cell response. This will not be detected by blood tests for antibodies. A person's immune response is affected by a number of factors, including health conditions and age.

Our blog on antibodies and immunity gives further information on the link between antibodies and immunity and the vaccine programme. Our blog on vaccine effectiveness provides information on the effectiveness of vaccinations against Alpha and Delta variants, which is based on research conducted by partners from the University of Oxford.

Measuring antibody positivity

Our 179 nanograms per millilitre (ng/ml) level is based on research by our academic partners, and reflects the percentage of adults who would have been likely to have a strong enough antibody response to provide some protection from getting a new COVID-19 infection with the Delta variant. This level is higher than our previously reported standard level of 42 ng/ml. Antibody levels below this do not mean that a person has no antibodies or immune protection at all. This antibody level was identified as providing a 67% lower risk of getting a new COVID-19 infection with the Delta variant after two vaccinations with either Pfizer or AstraZeneca vaccines, compared with someone who was unvaccinated and had not had COVID-19 before. It is unlikely that this level will provide equivalent protection against the Omicron variant, and we will keep the level used in our analysis of antibodies under regular review.

The test used for spike antibodies measures their concentration in ng/ml. The antibody level of 179 ng/ml corresponds to 100 binding antibody units (BAU)/ml, using the World Health Organization's (WHO) standardised units (enabling comparison across different antibody assays).

Further information on antibody test levels, and the link between antibodies and infections can be found in our recent blog post Relationship between COVID-19 infections and antibodies: What do the data show?