1. Main points
To provide estimates of coronavirus (COVID-19) positivity over the Christmas period, we have published headline results in a shortened version of our usual release.
Today, we have published new data that show in the week ending 23 December 2021:
In England, the percentage of people testing positive continued to increase; we estimate that 2,024,700 people in England had coronavirus (COVID-19) (95% credible interval: 1,951,200 to 2,096,300), equating to around 1 in 25 people.
In Wales, the percentage of people testing positive continued to increase; we estimate that 76,500 people in Wales had COVID-19 (95% credible interval: 65,100 to 89,200), equating to around 1 in 40 people.
In Northern Ireland, the percentage of people testing positive increased; we estimate that 47,500 people in Northern Ireland had COVID-19 (95% credible interval: 37,800 to 58,600), equating to around 1 in 40 people.
In Scotland, the percentage of people testing positive continued to increase; we estimate that 135,400 people in Scotland had COVID-19 (95% credible interval: 117,400 to 154,800), equating to around 1 in 40 people.
In England, COVID-19 infections increased across all age groups and were highest among those aged two years to school Year 6 and those aged 25 to 34 years; the high infections for those aged two years to school Year 6 are more likely to be compatible with the Delta variant, whereas the high infections for those aged 25 to 34 years are more likely to be compatible with the Omicron variant, as shown by separate analysis.
COVID-19 infections increased across all regions of England, with the highest infection levels seen in London (1 in 15) and the lowest in the North East of England (1 in 45).
COVID-19 infections compatible with the Omicron variant continued to increase rapidly across England, Wales, Northern Ireland and Scotland, and Omicron is now the most common variant in England and Scotland.
Figure 1: COVID-19 infections compatible with the Omicron variant continued to increase rapidly across England, Wales, Northern Ireland and Scotland in the week ending 23 December 2021
Modelled percentage of positive cases compatible with the Delta variant, and compatible with the Omicron variant, based on nose and throat swabs, daily, 12 November to 23 December 2021, UK
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Notes:
- All results are provisional and subject to revision.
- These statistics refer to infections occurring in private households, and exclude infections reported in hospitals, care homes and/or other communal establishments.
- Omicron variant-compatible positives are defined as those that are positive on the ORF1ab-gene and N-gene, but not the S-gene. Delta variant-compatible positives are defined as those that are positive on the ORF1ab, N-gene and S-gene, as well as gene patterns N+S and ORF1ab+S.
- Data should be treated with caution. Not all cases positive on the S-gene will be the Delta variant, but some cases with pattern ORF1ab+N will also be the Delta variant where the S-gene was not detected for other reasons, such as low viral load.
3. Glossary
Credible interval
A credible interval gives an indication of the uncertainty of an estimate from data analysis. The 95% credible intervals are calculated so that there is a 95% probability of the true value lying in the interval.
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4. Measuring the data
Reference dates
This week, the reference week is 17 to 23 December 2021 and the reference day is Monday 20 December 2021. More information on reference weeks and days can be found in the Measuring the data section of our Coronavirus (COVID-19) Infection Survey, UK: 23 December 2021 bulletin.
Data for a longer time series
A longer time series from earlier data can be found in our usual weekly Coronavirus (COVID-19) Infection Survey datasets for England, Wales, Northern Ireland and Scotland.
Survey fieldwork
Survey fieldwork for the pilot study began in England on 26 April 2020. Fieldwork began on 29 June 2020 in Wales, 26 July 2020 in Northern Ireland, and 21 September 2020 in Scotland.
Other Coronavirus Infection Survey (CIS) analysis and studies
This study is one of a number of studies that look to provide information around the coronavirus pandemic within the UK. For information on other studies see Section 11: Measuring the data in our previous bulletin, published 30 April 2021.
Quality
More quality and methodology information on strengths, limitations, appropriate uses, and how the data were created is available in our methods article and the Coronavirus (COVID-19) Infection Survey QMI.
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