2.1 Episodes of influenza, RSV and COVID-19

The number of new influenza episodes decreased in week 51, with 883 unique episodes identified. There were 1,105 episodes reported in week 50. There were 135 new RSV episodes identified in week 51, an increase from week 50 when 119 episodes were identified (Figure 2.1).

Influenza and RSV episode rates by age groups are shown in (Figure 2.2). The highest influenza episode rate in week 51 was in 0-4 age group (182.2 per 100,000 population). The highest RSV episode rate in week 51 was also in the 0-4 age group (90.2 per 100,000 population).

Influenza and RSV episode rates across local government districts (LGD) are shown in (Figure 2.3). Causeway Coast and Glens had the highest influenza episode rate in week 51 (60.0 per 100,000 population). Ards and North Down had the highest RSV episode rate in week 51 (11.6 per 100,000 population).

The number of new COVID-19 episodes decreased in week 51, with 34 unique episodes identified. There were 58 episodes reported in week 50 (Figure 2.1).

COVID-19 episode rates by age groups are shown in (Figure 2.2). The highest COVID-19 episode rate in week 51 was in the 75+ age group (9.9 per 100,000 population).

COVID-19 episode rates across LGD are shown in (Figure 2.3). Armagh City, Banbridge and Craigavon had the highest COVID-19 episode rate in week 51 (5.0 per 100,000 population).

Supplementary tables of unique episodes and weekly episode rates are shown at the end of this report.

Figure 2.1: Weekly number of unique episodes of influenza, RSV and COVID-19 by epidemiological week

Figure 2.2: Weekly episode rates of influenza, RSV and COVID-19 per 100,000 population, by age group and epidemiological week

Figure 2.3: Weekly episode rates of influenza, RSV and COVID-19 per 100,000 population, by local government district and epidemiological week

2.2 Testing and positivity (%)

In week 51 there were 3,604 influenza tests, 934 of which were positive (25.9% positivity). This is a decrease from week 50 (29.4% positivity) (Figure 2.4). Influenza positivity in week 51 was highest in the 5-14 age group (38.5% positivity) (Figure 2.5).

There were 1,662 RSV tests, 137 of which were positive (8.2% positivity). This is an increase from week 50 (6.9% positivity) (Figure 2.4). RSV positivity in week 51 was highest in the 0-4 age group (31.1% positivity) (Figure 2.5).

There were 2,985 COVID-19 tests, 41 of which were positive (1.4% positivity). This is similar to week 50 (1.9% positivity) (Figure 2.4). COVID-19 positivity in week 51 was highest in the 75+ age group (2.1% positivity) (Figure 2.5).

Supplementary tables of testing and positivity are shown at the end of this report.

Figure 2.4: Weekly positivity for influenza, RSV and COVID-19, by epidemiological week

Shading represents 95% confidence intervals.

Figure 2.5: Weekly positivity for influenza, RSV and COVID-19, by age group and epidemiological week

Shading represents 95% confidence intervals.

In week 51 there were 375 rhinovirus tests, 42 of which were positive (11.2% positivity). This is an increase from week 50 (9.6% positivity) (Figure 2.6).

There were 375 adenovirus tests, 16 of which were positive (4.3% positivity). This is a slight increase to week 50 (3.8% positivity) (Figure 2.6).

There were 375 parainfluenza tests, seven of which were positive (1.9% positivity). This is a decrease to week 50 (3.1% positivity) (Figure 2.6).

There were 375 human metapneumovirus (hMPV) tests, 21 of which were positive (5.6% positivity). This is the same as week 50 (5.6% positivity) (Figure 2.6).

Figure 2.6: Weekly positivity for rhinovirus, adenovirus, parainfluenza and Human metapneumovirus, by year and epidemiological week

Shading represents 95% confidence intervals.

2.3 Influenza sub-typing

Of the 883 new influenza episodes identified in week 51, 16 were typed as Flu A (H1), 284 were Flu A (H3), 580 were Flu A (not subtyped) and three were Flu B (Figure 2.7).

A supplementary table of influenza sub-typing is shown at the end of this report.

Figure 2.7: Weekly number of unique episodes of influenza, by subtype and epidemiological week

2.4 Sentinel surveillance

Sentinel surveillance plays a role in monitoring and understanding the spread and impact of respiratory viruses like influenza and COVID-19 in the community. It involves a systematic and targeted approach to collect data from a geographical representative subset of GP practices (~15% population representative) to provide information about virus activity across NI.

In week 51, 66 samples were positive for influenza from 123 samples submitted for testing to the Regional Virus Laboratory (RVL) (53.7% positivity). Of these, two were typed as Flu A (H1), 55 were Flu A (H3) and nine were Flu A (not subtyped). Seven samples were positive for RSV from 123 samples submitted for testing (5.7% positivity). Two samples were positive for COVID-19 (2.1% positivity) from 95 samples submitted for testing (Table 1).

Total sentinel cases of influenza, RSV and COVID-19 by age group for the previous year are shown in (Figure 2.8), (Figure 2.9) and (Figure 2.10), and cumulatively for the 2025/26 influenza season in Table 2.

A supplementary table of testing and positivity is shown at the end of this report.

Figure 2.8: Weekly sentinel influenza cases, by age group and epidemiological week

Figure 2.9: Weekly sentinel RSV cases, by age group and epidemiological week

Figure 2.10: Weekly sentinel COVID-19 cases, by age group and epidemiological week

2.5 Non-sentinel surveillance

Non-sentinel surveillance is the monitoring of respiratory viruses from virology data collected from settings such as hospitals and GPs (excluding the sentinel GPs). This provides information about virus activity across NI.

In week 51, 868 samples were positive for influenza from 3,481 samples submitted for testing to laboratories across NI (24.9% positivity). Of these, 15 were typed as Flu A (H1), 269 were Flu A (H3), 582 were Flu A (not subtyped) and two were Flu B. 130 samples were positive for RSV from 1,539 samples submitted for testing (8.5% positivity). 39 samples were positive for COVID-19 from 2,890 samples submitted for testing (1.4% positivity) (Table 3).

Total non-sentinel cases of influenza, RSV and COVID-19 by age group for the previous year are shown in (Figure 2.8), (Figure 2.9) and (Figure 2.13), and cumulatively for the 2025/26 influenza season in Table 4.

A supplementary table of testing and positivity is shown at the end of this report.

Figure 2.11: Weekly non-sentinel influenza cases, by age group and epidemiological week

Figure 2.12: Weekly non-sentinel RSV cases, by age group and epidemiological week

Figure 2.13: Weekly non-sentinel COVID-19 cases, by age group and epidemiological week

2.6 SARS-CoV-2 variants

In the 8 weeks 13 October 2025 to 07 December 2025, 121 COVID-19 samples were sequenced. Of these, 61 were XFG (50.4% of all sequenced samples), 22 were LP.8.1 (18.2% of all sequenced samples), 21 were XFG.3 (17.4% of all sequenced samples), 14 were NB.1.8.1 (11.6% of all sequenced samples), and 1 was BA.3 and XEC (both 0.8% of all sequenced samples). Due to small numbers of samples sequenced, the level of confidence in precision of the estimate is low, and the percentages of each variant may change as further results become available.A more detailed COVID-19 Genomics Bulletin containing a further breakdown of sub-lineages is published weekly.

Parent lineages displayed are subject to change based on lineages under monitoring by the UKHSA horizon scanning team.

Figure 2.14: Total number of sequenced variants of COVID-19 by Pangolin lineage, by epidemiological week

Recombinant refers to any recombinant lineage, starting “X”, that does not fall under the parent lineage of a defined variant.

3.1 Consultation rates for influenza/influenza-like-illness (‘flu/ILI’)

The general practice (GP) flu/ILI consultation rate during week 51 was 50.4 per 100,000 population. This is a decrease from week 50 (57.6 per 100,000 population). Rates are at moderate activity levels (25.8 to <55.2 per 100,000 population) (Figure 3.1).

The highest rate in week 51 was in the 0-4 age group (131.5 per 100,000 population) (Figure 3.2).

The highest rate in week 51 was in the Western Trust (92.2 per 100,000 population) (Figure 3.3).

Supplementary tables of GP consultation rates are shown at the end of this report.

Figure 3.1: Northern Ireland GP consultation rates for ‘flu/ILI’, 2021/22 – 2024/25

The baseline MEM threshold for Northern Ireland is <10.7 per 100,000 population for 2025-26. Low activity is 10.7 to <25.8, moderate activity 25.8 to <55.2, high activity 55.2 to <77.1 and very high activity is >77.1 per 100,000 population.

Figure 3.2: GP consultation rates for ‘flu/ILI’, by age group, 2022/23 – 2025/26

Figure 3.3: GP consultation rates for ‘flu/ILI’, by HSCT, 2022/23 – 2025/26

3.2 Consultation rates for acute respiratory infection (ARI)

The GP ARI consultation rate during week 51 was 281.2 per 100,000 population. This is an increase to week 50 (277.3 per 100,000 population) (Figure 3.4).

The highest rate in week 51 was in the 0-4 age group (1,271.3 per 100,000 population) (Figure 3.5).

The highest rate in week 51 was in the Western Trust (423.9 per 100,000 population) (Figure 3.6).

Supplementary tables of GP consultation rates are shown at the end of this report.

Figure 3.4: Northern Ireland GP consultation rates for ARI, 2022/23 – 2025/26

Figure 3.5: GP consultation rates for ARI, by age group, 2022/23 – 2025/26

Figure 3.6: GP consultation rates for ARI, by HSCT, 2022/23 – 2025/26

3.3 Consultation rates for COVID-19

The GP COVID-19 consultation rate during week 51 was 1.0 per 100,000 population. This is the same as week 50 (1.0 per 100,000 population) (Figure 3.7).

The highest rate in week 51 was in the 75+ age group (2.9 per 100,000 population) (Figure 3.8).

The highest rate in week 51 was in the Southern (1.4 per 100,000 population) (Figure 3.9).

Supplementary tables of GP consultation rates are shown at the end of this report.

Figure 3.7: Northern Ireland GP consultation rates for COVID-19, 2022/23 – 2025/26

Figure 3.8: GP consultation rates for COVID-19, by age group, 2022/23 – 2025/26

Figure 3.9: GP consultation rates for COVID-19, by HSCT, 2022/23 – 2025/26

4.1 Influenza, RSV and COVID-19 care homes outbreaks

There were eight confirmed outbreaks reported in care home settings to the Public Health Agency (PHA) Health Protection Acute Response Duty Room in week 51. Seven were Flu A (not subtyped) and one Flu A (H3). In week 50 there were seven outbreaks reported (six were Flu A (not subtyped) and one was Flu A (H3) (Figure 4.1).

Figure 4.1: Weekly number of confirmed influenza, RSV and COVID-19 outbreaks, by epidemiological week

5.1 Admissions and occupancy

There were 388 new community-acquired emergency hospital admissions during week 51 (Figure 5.1). Of these, 306 were influenza A, two influenza B, 66 were RSV and 14 were COVID-19. In week 50 there were 404 hospital admissions. Of these, 331 were influenza A, 60 were RSV and 13 were COVID-19.

Community-acquired emergency hospital admission rates in week 51 were highest in the 75+ age group for influenza (68.6 per 100,000 population), the 0-4 age group for RSV (51.3 per 100,000 population), and the 75+ age group for COVID-19 (5.3 per 100,000 population) (Figure 5.2).

Supplementary tables of emergency hospital admissions and rates by age group are shown at the end of this report.

Figure 5.1: Weekly number of community-acquired emergency influenza, RSV and COVID-19 hospital admissions, by epidemiological week

Figure 5.2: Weekly community-acquired emergency influenza, RSV and COVID-19 hospital admission rates per 100,000 population, by age group and epidemiological week

Community-acquired emergency influenza inpatients have remained broadly stable. For RSV and COVID-19, community-acquired emergency inpatients have also remained stable.(Figure 5.3). Community-acquired emergency inpatients by age group for the previous year are shown in (Figure 5.4).

Figure 5.3: Influenza, RSV and COVID-19 community acquired emergency inpatients, by day

Figure 5.4: Influenza, RSV and COVID-19 community acquired emergency inpatients, by age group and day

6.1 Deaths related to influenza and/or pneumonia

NISRA death statistics are published weekly. These statistics report on deaths where influenza and/or pneumonia was mentioned anywhere on the death certificate. As a result, the counts will reflect deaths where influenza or pneumonia has contributed to a death but was not necessarily the underlying cause of the death.

The latest data is available for week ending 12 December 2025. In week 50, 82 influenza and/or pneumonia related deaths from 389 deaths were reported (21.1%). This is higher to the previous week (20.1%) (Figure 6.1).

Figure 6.1: Weekly deaths and percentage of registered deaths related to influenza and/or pneumonia, to most recent registration week

6.2 Deaths related to COVID-19

NISRA death statistics report on deaths where COVID-19 was mentioned anywhere on the death certificate. As a result, the counts will reflect deaths where COVID-19 has contributed to a death but was not necessarily the underlying cause of the death.

The latest data is available for the week ending 12 December 2025. In week 50, one COVID-19 related death from 389 deaths were reported (0.3%). This is the same as the previous week (0.3%) (Figure 6.2).

Figure 6.2: Weekly deaths and percentage of registered deaths related to COVID-19, to most recent registration week

6.3 Excess Mortality

NISRA use the UK-wide methodology to report on excess deaths as advised by the Office for National Statistics (ONS).

EuroMOMO is a European mortality monitoring activity, aiming to detect and measure excess deaths related to seasonal influenza, pandemics and other public health threats. Reports on excess deaths across Europe and the United Kingdom are published weekly.

9.1 Presentation of data

Unless otherwise stated, data are presented using epidemiological weeks (a standardised method of counting weeks [Monday-Sunday] to allow for the comparison of data year after year). This is dependent on the data available. The data included in this report are the most up to date data available at the time of the report; however, this is subject to change as the data are subject to ongoing quality assurance.

9.2 Virology surveillance

All virology data provided here are preliminary. Virology data for prior weeks, as included in this or future reports, are subject to updates based on laboratory returns received after the last report was produced. The current report offers the most current information available.

Rates per 100,000 population are calculated using the NISRA 2021 Mid-Year Population Estimates.

9.3 SARS-CoV-2 genomics

A subset of SARS-CoV-2 positive PCR samples are sent to sequencing laboratories in Belfast Health and Social Care Trust and Queen’s University Belfast for sequencing. On 29th November 2022 the lineage assignment algorithm was switched from PangoLEARN to UShER for lineage counts. PangoLEARN uses a machine learning algorithm, whereas UShER uses phylogenetic placement and produces fewer unassigned lineages. This switch has been applied retrospectively, therefore total counts for all lineages have been affected. A more detailed COVID-19 Genomics Bulletin containing a further breakdown of sub-lineages is published weekly.

9.4 Primary care surveillance

Consultation rates for influenza/influenza-like-illness (‘flu/ILI’), acute respiratory infection (ARI) and COVID-19

GP in-hours consultation data with ~95% coverage of the NI population is auto-extracted weekly from the General Practitioner Intelligence Platform (GPIP). This data includes weekly aggregate consultations for ‘flu/ILI’, ARI, and COVID-19, and includes weekly registered patients. The data is available for different Health and Social Care Trusts, and by age and sex.

9.5 Community surveillance

Care home outbreaks

PHA conducts surveillance of outbreaks across multiple settings, including care homes (nursing homes and residential homes) in NI that are registered with the Regulation and Quality Improvement Agency (RQIA). All care homes have a requirement to notify the PHA Health Protection duty room of suspected outbreaks of any infectious disease. A confirmed outbreak of influenza, RSV or COVID-19 can be defined as where there are two or more confirmed cases with onset within a 14 day period, where transmission within the Care Home facility is considered the likely cause.

9.6 Secondary care surveillance

Influenza and RSV

Community-acquired influenza and RSV emergency admissions to acute hospitals are estimated by combining data from the Patient Administration System (PAS), EPIC and virological reports in the Northern Ireland Health Analytics Platform (NIHAP). Admissions are counted where there was a positive test up to seven days before admission or up to one day after admission, and the method of admission was ‘Emergency’. The number of inpatients is counted at midnight. Admissions and occupancy refer to the first admission per infection episode.

COVID-19

Community-acquired COVID-19 emergency admissions to acute hospitals are estimated by combining data from from PAS, EPIC and virological reports in NIHAP. Admissions are counted where there was a positive PCR or lateral flow test up to 14 days before admission or up to one day after admission. The number of inpatients is counted at midnight. Admissions and occupancy refer to the first admission per infection episode, including transfers between hospitals. The method used in this report is different to that previously reported by the Department of Health’s COVID-19 dashboard, which used administrative coding to identify COVID-19 admissions.

9.7 Mortality surveillance

NISRA death statistics are published weekly, and include weekly counts of deaths related to influenza and/or pneumonia (new from 31 January 2025), and deaths related to COVID-19. This enables comparisons with weekly information published by the Office for National Statistics (ONS) covering England and Wales.

The statistics report on deaths where influenza and/or pneumonia, or COVID-19, was mentioned anywhere on the death certificate. As a result, the counts will reflect deaths where these diseases have contributed to a death but was not necessarily the underlying cause of the death.

9.8 Vaccine Effectiveness methodology

Study setting and population

This study was conducted including data from Scotland, Wales, and Northern Ireland. The study population included all individuals aged ≥2 years who had a hospital admission and a recorded influenza RT-PCR test during epidemiological weeks 40 to 47 of the 2025/26 season.

Data sources

Influenza testing

In Northern Ireland, influenza testing data were sourced from the regional influenza surveillance system, which collates virological reports from the Regional Virus Laboratory (RVL) and all local Health and Social Health (HSC) Trust laboratories. Influenza admissions were defined as admissions in which a positive influenza test was obtained up to 14 days before or within 48 hours following the date of hospital admission.

Scottish influenza laboratory testing data was derived from Electronic Communication of Surveillance in Scotland (ECOSS) dataset. For this analysis, ECOSS data was extracted 03 December 2025. The case definition for a positive influenza test were patients with a positive test 14 days before or within 48 hours of hospital admission. This was limited to emergency care admissions.

In Wales, influenza testing data were provided from the Public Health Wales national microbiology Datastore (a repository containing all PCR diagnostic data across NHS Wales Microbiology laboratories). Testing data were deduplicated to 28-day episodes, with sample date of earliest positive influenza test retained. Point of care testing data are not currently included, however national guidance in Wales encourages confirmation of influenza positive point of care tests through multiplex PCR methods (these test results are included).

Vaccination status

In Northern Ireland, vaccination status was obtained from the NI Vaccine Management System (VMS) and defined at the time of specimen collection. Individuals were classified as vaccinated if they had received a seasonal influenza vaccine at least 14 days before their sample date. Those with no record of influenza vaccination prior to specimen collection were considered unvaccinated. Patients who tested positive for influenza within 14 days of vaccination, classified as partially vaccinated, were excluded from the main analysis to allow sufficient time for an adequate immune response to develop.

Vaccination status in Scotland was derived from the vaccination management tool (VMT) used to record influenza vaccination in those ≥ 2 years old. Vaccination status was determined at the time of specimen collection. Patients were considered vaccinated if they had received a dose of the seasonal influenza vaccine at least 14 days prior to their sample date. Those with no record of influenza vaccination before the sample date were considered unvaccinated. Patients who tested positive for influenza within 14 days of receiving the vaccine – considered partially vaccinated – were excluded from the main analysis, to allow for the time required for an adequate immune response to develop.

In Wales, vaccination statuses were obtained from the Welsh Immunisation System (WIS) and linked to admission and virological test data using patient NHS number. WIS contains vaccination status data for all Wales residents registered for NHS care, who are eligible for free influenza vaccination as part of the annual NHS programme. WIS includes vaccination data from both GPs and community pharmacies. Vaccination status was defined at the time of specimen collection. Individuals were classified as vaccinated if they had received a seasonal influenza vaccine at least 14 days before their sample date. Those with no record of influenza vaccination prior to specimen collection were considered unvaccinated. Patients who tested positive for influenza within 14 days of vaccination, classified as partially vaccinated, were excluded from the main analysis to allow sufficient time for an adequate immune response to develop.

Hospitalisation

Patients in Northern Ireland were classified as hospitalised if they had a hospital admission recorded in the Epic electronic health record system occurring between epidemiological weeks 40 and 47.

Scottish patients were considered hospitalised if they had a Rapid Preliminary Inpatient Data (RAPID) emergency admission recording taking place between epidemiological weeks 40 and 47.

In Wales, patients were classified as hospitalised if they had a recorded admission in ICNet with a linked virological test result occurring between epidemiological weeks 40 and 47

Exclusions

Patients who were partially vaccinated (i.e., received influenza vaccine <14 days before sample collection) were excluded from the main vaccine effectiveness analysis. Individuals with a positive SARS-CoV-2 test were excluded from the control group.

Covariates

Due to limitations in data availability for deprivation and at-risk status across nations, pooled estimates containing data from Scotland, Wales and Northern Ireland were adjusted for sex, epidemiological week and region.

Statistical methods

A binomial regression model was used to estimate odds ratios for influenza A positivity by vaccination status. To explore effect modification, we included an interaction term between vaccination status and region/age group.

Vaccine effectiveness (VE) was calculated as:

VE = (1 – adjusted odds ratio) x 100%

Due to the inability to ascertain eligibility status in at-risk populations ages 18-64 years, vaccine effectiveness in this eligible group is not yet available. Future analyses will explore other this and factors underlying vaccine effectiveness including product type and waning.

10.1 Unique episodes of influenza, RSV and COVID-19, by epidemiological week, over a six week period

10.2 Influenza, RSV and COVID-19 episode rates per 100,000 population, by age group, over a six week period

10.3 Influenza, RSV and COVID-19 episode rates per 100,000 population, by local government district, over a six week period

10.4 Total tests and positivity for influenza, RSV and COVID-19, by epidemiological week, over a six week period

10.5 Positivity for influenza, RSV and COVID-19, by age group and epidemiological week, over a six week period

10.6 Unique episodes of influenza, by subtype, over a six week period

10.7 Total sentinel tests and positivity for influenza, RSV and COVID-19, by epidemiological week, over a six week period

10.8 Total non-sentinel tests and positivity for influenza, RSV and COVID-19, by epidemiological week, over a six week period

10.9 Number of sequenced samples for variants in Northern Ireland

This table only shows counts for lineages with 10 or more sequenced samples from 2024 - 51 onwards. Lineage counts include provisional and confirmed sequencing samples. Lineage calls are subject to change following analysis of genomic sequence results, which may result in fluctuations in lineage counts.

10.10 Flu/ILI consultation rates per 100,000 population, by age group, over a six week period

10.11 Flu/ILI consultation rates per 100,000 population, by Health and Social Care Trust, over a six week period

10.12 ARI consultation rates per 100,000 population, by age group, over a six week period

10.13 ARI consultation rates per 100,000 population, by Health and Social Care Trust, over a six week period

10.14 COVID-19 consultation rates per 100,000 population, by age group, over a six week period

10.15 COVID-19 consultation rates per 100,000 population, by Health and Social Care Trust, over a six week period

10.16 Number of community-acquired emergency hospital admissions, over a six week period

10.17 Community-acquired emergency hospital admission rates per 100,000 population, by age group, over a six week period