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

Date published: 11 March 2022

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 Northern Ireland for the week up to the 5 March 2022. 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.

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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 (27 February – 5 March 2022), it is estimated that 143,800 people in Northern Ireland had COVID-19 (95% credible interval: 124,700 to 163,900).
  • this equates to 7.84% of the population (95% credible interval: 6.80% to 8.93%) or around 1 in 13 people (95% credible interval: 1 in 15 to 1 in 11).
  • modelling suggests the percentage of people testing positive increased in the week ending 5 March in Northern Ireland.
  • in the latest six-week period, there were 16,745 swab tests taken in total from 11,954 participants. Of these, 1,017 participants tested positive from 734 different households.
  • in the latest two-week period, of the 4,992 participants in the study, 294 tested positive from 230 households.
  • the trend in the percentage of people testing positive in Northern Ireland increased in those aged 40 years or over but was uncertain in all others in the most recent week.
  • in the week ending the 5 March 2022 (6 March 2022 for Scotland), the percentage of infections compatible with the Omicron BA.2 variant increased in England, Wales, Northern Ireland and Scotland; the percentage of infections compatible with the Omicron BA.1 variant decreased in England, Wales and Scotland and the trend was uncertain in Northern Ireland (see below for more information on the variant analysis undertaken).

Variant analysis

The World Health Organization (WHO) have defined names for Variants of Concern. These are variants that the UK government has under surveillance. You can find out more in the SARS-CoV-2 variants of concern and variants under investigation in England briefing document (PDF, 2.51MB).

UK Variants of Concern:

  • Alpha: B.1.1.7
  • Beta: B.1.351
  • Gamma: P.1
  • Delta: B.1.617.2 and its genetic descendants
  • Omicron: B.1.1.529 (which includes sublineages BA.1, BA.1.1, BA.2 and BA.3)

The Omicron variant BA.1 has changes in one of the three genes that the coronavirus swab used in the survey tests detects, known as the S-gene. This means the S-gene is no longer detected by the current test. When there is a high viral load (for example, when a person is most infectious), not detecting the S-gene in combination with detecting the other two genes (ORF1ab and N-genes) is a reliable indicator of this Omicron BA.1 variant. However, as the viral load decreases (for example, if someone is near the end of their recovery from the infection), not detecting the S-gene is a less reliable indicator of this Omicron variant. The sub-variant Omicron BA.1.1 also mostly has gene pattern ORF1ab + N. Therefore, gene pattern matching used in the main variant analysis cannot distinguish between Omicron BA.1 and Omicron BA.1.1.

The Omicron variant BA.2 does not have changes in the S gene, and therefore all three genes, or the S-gene and either ORF1ab or N, will usually be detected in infections with this variant. Delta also does not have changes in the S-gene, and therefore the same sets of genes will usually be detected with Delta and Omicron BA.2. However, the genome sequencing analysis shows that almost all infections where the S-gene is detected are now Omicron BA.2. For this reason, we now label cases with gene patterns ORF1ab + N + S, ORF1ab + S and N + S as “compatible with the Omicron BA.2 variant” in our main variant analysis. This is because estimates are now likely to mostly reflect trends in Omicron BA.2, although other variants may still be having a very small impact. The Omicron BA.2 variant is now the most common variant in England, Northern Ireland and Scotland.

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 in the methodology article.


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
    Belfast BT4 3SQ
    Telephone:          028 9052 2340         E-mail:
  9. For media enquiries please contact the DoH Press Office by email
  10. Follow us on Twitter @healthdpt.
  11. The Executive Information Service operates an out of hours service For Media Enquiries Only between 1800hrs and 0800hrs Monday to Friday and at weekends and public holidays. The duty press officer can be contacted on 028 9037 8110.

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