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 2 June 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.

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).

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.

The World Health Organization (WHO) have defined names for variants of concern.

Currently, variants under surveillance in the UK are:

The Coronavirus (COVID-19) Infection Survey: technical dataset includes analysis of the genetic lineages of coronavirus seen in the samples that are sequenced. Since March 2022, Omicron BA.2 infections have been the most common in all UK countries. Between 2 and 29 May 2022, 90.7% of all sequenced COVID-19 infections were Omicron BA.2 infections, 3.8% were Omicron BA.5 infections, 3.4% were Omicron BA.4 infections, and 0.5% were Omicron BA.1 (or its sub-lineages) infections.

In response to an increase in the COVID-19 Omicron variants BA.4 and BA.5, we have reintroduced the main variant analysis in this bulletin. The following main variant analysis is not based on genome sequencing but is based on whether the S gene is detected in the swab tests.

The Omicron variants BA.1, BA.4 and BA.5 have changes in one of the three genes that the coronavirus survey swab test detects, which means the S-gene is no longer detected. 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 these variants. 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 these Omicron variants. 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.

Across all four UK countries, the percentage of people testing positive for COVID-19 compatible with Omicron variants BA.1, BA.4 and BA.5 increased in the week ending 2 June 2022. In the same week, the percentage of people testing positive for COVID-19 compatible with Omicron variant BA.2 decreased in England and Wales, and the trend was uncertain in 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 the Coronavirus (COVID-19) Infection Survey methods article provides more detail about how the virus' genetic material is sequenced.