1 Summary

• In the 8 epidemiological weeks (09 December 2024 to 30 January 2025), 78 COVID-19 samples were sequenced in Northern Ireland.

• The current most common SARS-CoV-2 variant in Northern Ireland is XEC (V-23DEC-01), with 18 sequenced samples, or 100% of all sequenced samples (100% of those with a lineage assigned) in the week commencing 23 December 2024.

• More information about prevalence and growth rates of SARS-CoV-2 lineages circulating in the UK can be found in UKHSA reports published here.

2 Current Variant View - last 8 weeks

This section summarises the SARS-CoV-2 sequencing data for Northern Ireland for the last 8 weeks of sequencing data available (09 December 2024 to 30 January 2025).

In the last 8 weeks of sequencing data, the following parent lineages have been detected: XEC, KP.3, XEC.2, JN.1, KP, XEC.4, and XEC.5. The number of sequenced samples can be seen in Table 2.1 and Figure 2.1, and the numbers as a percentage of total sequenced samples are shown in Figure 2.2. The age group distribution by parent lineage is shown in Figure 2.3.

Please note that numbers of sequenced samples per week may change retrospectively due to the delay in sequencing.

Recombinant refers to any lineage starting with “X” that does not fall under any other parent lineage definition.

Figure 2.1: Sequenced COVID-19 cases in Northern Ireland, by parent lineage and day, for the last 8 weeks of sequencing data

Figure 2.2: Percentage of sequenced COVID-19 cases in Northern Ireland, by variant and epidemiological week, for the last 8 weeks of sequencing data

Figure 2.3: Total number of sequenced COVID-19 samples in Northern Ireland by age group, faceted by parent lineage over the last 8 weeks of sequencing data

This chart only shows counts for lineages with at least 5 sequenced samples in a given age group.

Age band information is not available for all sequences, so age band distributions should be interpreted with caution.

3 Variant View - last 12 months

This section summarises the COVID-19 sequencing data for Northern Ireland over the past 12 months (28 January 2024 to 30 January 2025).

The number of sequenced samples over the past 12 months can be seen in Figure 3.1 and supplementary Table 6.2, and the numbers as a percentage of total sequenced samples are shown in Figure 3.2. The age-sex distribution by parent lineages is shown in Figure 3.3.

Figure 3.1: Sequenced COVID-19 cases in Northern Ireland, by variant and epidemiological week for the last 12 months

Figure 3.2: Percentage of sequenced COVID-19 samples in Northern Ireland by epidemiological week for the last 12 months

Figure 3.3: Total number of sequenced COVID-19 samples in Northern Ireland by age group and sex, by parent lineage over the last 12 months

This chart only shows counts for lineages with at least 5 sequenced samples in a given age group.

4 Percentage of Specimens Sequenced

Not all PCR samples are sequenced; sequencing can only be carried out on samples that have a sufficiently high viral load, which is largely determined by when the sample is taken during the course of the infection. Other factors affecting how many samples are sequenced include volume of sample available, sample quality, and sequencing laboratory capacity.

The number of COVID-19 positive PCR samples (sequenced and not sequenced) in Northern Ireland over the past 12 months (22 January 2024 to 27 January 2025) is shown in Figure 4.1. The percentage of COVID-19 positive PCR samples that have been sequenced in on a weekly basis over the past 12 months is shown in Figure 4.2, with 13.79% sequenced (4 week rolling average of 15.17%) in the week commencing 27 January 2025.

Figure 4.1: Count of sequenced and not sequenced positive COVID-19 PCR samples in Northern Ireland over the last 12 months

Figure 4.2: Percentage of positive COVID-19 samples sequenced in Northern Ireland over the last 12 months

5 Key Definitions and Interpretation

6 Appendix