Coronavirus (Covid-19) Infection Survey, Northern Ireland: Weekly Report

The Department of Health today published the next in the series of weekly results from its COVID-19 Infection Survey (CIS). The findings set out in this report relate to modelled positivity estimates for NI for the week up to the 14 January 2023. The aims of the CIS are to estimate how many people have the infection and the number of new cases that occur over a given time as well as estimating how many people have developed antibodies to COVID-19.

The survey over time will help track the extent of infection and transmission of COVID-19 among people in the community population (those in private residential households).

Key Findings

Due to the relatively small number of tests and positive swab results within our sample, credible intervals are wide and therefore results should be interpreted with caution.

• During the most recent week of the study (8 January – 14 January 2023), it is estimated that 56,500 people in Northern Ireland had COVID-19 (95% credible interval: 45,800 to 68,500).
• This equates to 3.08% of the population (95% credible interval: 2.50% to 3.74%), a decrease from 4.22% in the week ending 10 January 2023, or around 1 in 30 people (95% credible interval: 1 in 40 to 1 in 25).
• Modelling suggests the percentage of people testing positive continued to decrease in the week ending 14 January 2023 in Northern Ireland.

Variant analysis

Currently, the variants under surveillance in the UK are:

• Omicron, including sub-lineages BA.2, BA.4 and BA.5, and their sub-lineages.

The cycle threshold (Ct) value reflects the quantity of virus (also known as viral load) found in a swab test. A lower Ct value indicates a higher viral load. The latest Ct values of coronavirus (COVID-19) positive tests, as well as analysis of the genetic lineages of COVID-19 seen in the samples that are sequenced, are provided in the Coronavirus (COVID-19) Infection Survey: technical dataset.

Since the end of June 2022, most COVID-19 infections in the UK have been Omicron variant BA.5 or its sub-lineages, the majority of which are now the sub-lineage BQ.1. In the week ending 8 January 2023, BQ.1 comprised 46.3%, and other BA.5 variants (and sub-lineages, excluding BQ.1) comprised 9.0% of all sequenced COVID-19 infections. The variant BA.2.75 and its sub-lineages (that includes XBB and its sub-lineages, and CH.1.1 and its sub-lineages) comprised 42.2%, with the sub-lineage CH.1.1 and its sub-lineages comprising 24.6%, and the sub-lineage XBB and its sub-lineages comprising 3.3% of sequenced infections in the week ending 8 January 2023.

More information on how variants from positive tests on the survey are measured can be found in the ONS Understanding COVID-19 Variants blog and the Coronavirus (COVID-19) Infection Survey methods article.

The last published main variant analysis was included in COVID-19 Infection Survey, Northern Ireland: Weekly Report 8 July 2022. This showed a very high proportion of infections compatible with the BA.4 and BA.5 variants, so a breakdown of infections by variants is not included in this release. Infections by variant will continued to be monitored and analysis will be reintroduced when considered helpful.

Notes to editors: 

1. The Department of Health has been working along with the Public Health Agency, Northern Ireland Statistics and Research Agency and the Office for National Statistics (and its various survey partners) to extend the COVID-19 Infection Survey to Northern Ireland. Fieldwork in Northern Ireland began on 27 July 2020.
2. All results are provisional and subject to revision. Due to relatively small number of tests and positive swab tests within the sample, credible intervals are wide and therefore results should be interpreted with caution.
3. These statistics refer to infections reported in the community (i.e. private households). These figures exclude infections reported in hospitals, care homes and/or other communal establishments.
4. Estimates of the total national proportion of the population testing positive for COVID-19 are adjusted to be representative of the population of Northern Ireland that live in private residential households in terms of age, sex and region.
5. Weekly reports are to be published with findings from the COVID-19 Infection survey. It is anticipated that new and further analyses will be added to the weekly reports over time.
6. Further information about quality and methodology associated with the survey can be found on the ONS website.
7. This publication is available online at:
8. Additional information is available from:
   Information Analysis Directorate
   Department of Health
   Annex 2, Castle Buildings
   Stormont
   Belfast BT4 3SQ
   Telephone:    028 9052 2340         E-mail: statistics@health-ni.gov.uk

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