Tue, 04 Oct 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 NI for the week up to the 24 November 2021. 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 residences).

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 (18 November - 24 November), it is estimated that 41,100 people in Northern Ireland had COVID-19 (95% credible interval: 32,100 to 50,900). 
  • This equates to 2.24% of the population (95% credible interval: 1.75% to 2.77%) or around 1 in 45 people (95% credible interval 1 in 55 to 1 in 35).
  • Modelling suggests the percentage of people testing positive continued to increase in the week ending 24 November in Northern Ireland.
  • In the latest six-week period, there were 16,549 swab tests taken in total from 11,788 participants. Of these, 221 participants tested positive from 173 different households.
  • In the latest two-week period, of the 5,454 participants in the study, 104 tested positive from 82 households.

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, first identified in the UK
  • Beta: B.1.351, first identified in South Africa
  • Gamma: P.1, first identified in Brazil
  • Delta: B.1.617.2, first identified in India
  • Omicron: B.1.1.529, first identified in multiple countries

Infections compatible with the Delta variant have been the most common since the end of May 2021 in England, and since the end of July 2021 in all four UK countries. The most recent results show over 99% of all coronavirus (COVID-19) infections, where a genetic sequence could be obtained, were genetically compatible with the Delta variant or its descendants. Due to this high proportion with the same gene positivity pattern, a breakdown of infections by variant based on gene positivity patterns has not been included. The main variant analysis was last published on the 23 July 2021, where more details can be found.

To date, infections compatible with the new Omicron variant (B.1.1.529) have not been identified among the survey participants. It is only when there are sufficient participants testing positive with infections compatible with the Omicron variant that a meaningful estimate of the number of people infected in the population can be produced. This variant and other variants detected in the sample will continue to be monitored.

Infections by variant will continue to be monitored and the charts and analysis will be introduced when considered helpful.

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.

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