2.1 Episodes of COVID-19

Infection episodes detected through clinical testing reveal only a small fraction of the true number of cases, because only a minority of people who have COVID-19 disease are tested. We continue to monitor these because an increase may indicate increasing incidence or severity.

The number of new episodes is shown by week overall (Figure 2.1), as a rate per 100,000 population by age band over time (Figure 2.2), as a rate per 100,000 population by local government district (LGD) for the most recent week in a bar plot (Figure 2.3) and over a six week period (Figure 2.4). Supplementary tables of key figures are shown at the end of this document. There has been an increase in the number of new episodes in the current week, with 67 episodes identified in week 17 compared to 54 in the previous week. All age groups saw an increase in episode rates when compared to the previous week apart from the 70-79 year old age group which saw a decrease in episode rate. The highest episode rates per 100,000 population remain in the 80+ year-olds (21.4 per 100,000 population). Antrim and Newtownabbey, Belfast, Causeway Coast and Glens, Lisburn and Castlereagh and Mid Ulster all saw an increase in episode rates when compared to the previous week. Ards and North Down, Armagh City, Banbridge and Craigavon, Fermanagh and Omagh, Newry, Mourne and Down saw a decrease in episode rates when compared to the previous week while remaining areas saw no change.

Testing policy changes over time in NI will have an impact on the proportion of COVID-19 cases detected and may affect case rates and other indicators presented in this report. Since 2022, testing of most of the general population with COVID-19 symptoms has no longer been advised. This reduced volume of testing is consistent with the rest of the UK.

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

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

Figure 2.3: Episode rate of COVID-19 per 100,000 population by Local Government District, for week 17 2024

Figure 2.4: Weekly episode rates of COVID-19 per 100,000 population, by Local Government District, by epidemiological week

2.2 SARS-CoV-2 Genomics

An interactive dashboard of the genomics (variant types) of NI SARS-CoV-2 is available online here. It was created by Queen’s University Belfast, the Public Health Agency and the Wellcome Sanger Institute, funded by COG-UK. The weekly proportion of cases by lineage is shown (Figure 2.5).

For the week commencing 19th of February 2024, JN.1 accounts for 66.7% of all sequenced samples, BA.2.86 4.2% and BA.2 4.2%. 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. The latest updates on SARS-CoV-2 variants detected in the UK can be found online here.

Parent lineages displayed are subject to change based on lineages under monitoring by the UKHSA horizon scanning team. The latest variant report published by UKHSA online here provides further information about novel SARS-CoV-2 variants.

Further information about SARS-CoV-2 lineage prevalence and growth rates is published online here by UKHSA.

Figure 2.5: Proportion 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. This chart only shows counts for lineages with 10 or more sequenced samples from epidemiological year-week 2023 - 17 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.

This table only shows counts for lineages with 10 or more sequenced samples from epidemiological year-week 2023 - 17 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.

2.3 COVID-19 Outbreaks in Care Homes

There has been a decrease in the number of new outbreaks in the current week compared to the previous week; with 0 new outbreaks reported in week 17; compared to 4 in the previous week (Figure 2.6).

Figure 2.6: Weekly number of confirmed COVID-19 care home outbreaks, by epidemiological week

3.1 COVID-19 Admissions and Occupancy

There has been a decrease in the number of community acquired emergency COVID-19 hospital admissions, with 9 admissions in the current week compared to 11 in the previous week (Figure 3.1). The 0-9 year-old age group had the majority of community acquired emergency COVID-19 hospital admissions in week 17 (33.3%). There has been a general decreasing trend in the number of community acquired emergency COVID-19 inpatients since late December (Figure 3.2).

Figure 3.1: Weekly number of COVID-19 community acquired emergency admissions, by epidemiological week

Figure 3.2: COVID-19 community acquired emergency inpatients, by day

3.2 Medical Certificate of Cause of Death for COVID-19

The Northern Ireland Statistics and Research Agency (NISRA) provide the weekly number of registered COVID-19 deaths each Friday. In the week ending April 19 2024, there were 2 COVID-19 registered deaths; an increase when compared to the previous week (Figure 3.3). Further detail can be found online here.

Figure 3.3: Weekly number of registered COVID-19 deaths

Figures may be impacted by General Registration Office closures over public holidays.

3.3 All-cause excess deaths

From week 45 of 2023 onward, based on NISRA death registrations and the EuroMoMo model, there have been excess deaths reported in weeks 4, 5 and 6, particularly in those aged 65+. Despite delay correction, reported mortality data are still provisional due to the time delay in registration and observations which can vary from week to week; not all registrations for the current week will have been included this bulletin (Figure 3.4).

Figure 3.4: Weekly observed and expected number of all-cause deaths in all ages, week 50 2018 - week 17 2024

5.1 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.

5.2 Infection Episodes

From 22nd April 2022, Polymerase Chain Reaction (PCR) testing was no longer available to the majority of the population with COVID-19 symptoms. From 22nd August 2022, most of the general population with COVID-19 symptoms were no longer advised to take a lateral flow test. These processes are in line with the Test, Trace and Protect Transition plan, published in March 2022, aiming to make testing more proportionate and targeted to protect the most vulnerable within the population. On 27 February 2024 new COVID-19 testing guidance came into effect. It reduces the circumstances in which testing is performed. More information is available here. These and other testing policy changes over time in NI will have an impact on the proportion of COVID-19 cases detected and may affect case rates and other indicators presented in this report.

Confirmed COVID-19 episodes from Pillars 1 and 2 are presented in this report. Infection episodes are defined by a rolling 90-day period between positive test results (any test method, sourced from the NI COVID-19 combined testing register), with the episode beginning with the earliest positive specimen date. Subsequent positive specimen dates for the same individual within 90 days of the last are included in the one episode. Positive specimens for the same individual more than 90 days after the last are counted in a separate episode.

Rates per 100,000 population are calculated using the NISRA 2020 Mid-Year Population Estimates for age groups, and NISRA 2021 Mid-Year Population Estimates for LGDs.

5.3 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 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.

5.4 Care home outbreak surveillance

PHA conducts surveillance of outbreaks in care homes (nursing homes and residential homes) in NI that are registered with the Regulation and Quality Improvement Agency. 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 COVID-19 can be defined as as where there are two or more confirmed COVID-19 cases with onset within a 14 day period, where transmission within the Care Home facility is considered the likely cause.

5.5 Admissions and Occupancy

Community-acquired COVID-19 emergency admissions to acute hospitals are estimated by combining data from the NI COVID-19 Combined Testing Register and Patient Administration System (PAS). 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, 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. The methodology 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. It is not currently possible to distinguish emergency from other sources of admission in the SEHSCT hospital data, this follows the introduction of a new electronic healthcare record on 06/11/2023. For this report, all community-acquired COVID-19 admissions for SEHSCT are included. Work is ongoing to adapt systems to new data sources.

5.6 Medical Certificate of Cause of Death for COVID-19

PHA report weekly counts of COVID-19 death registrations in NI, as published by NISRA online here. Deaths occurring in NI are registered on the NI General Register Office’s Registration System (NIROS). Daily extracts of registration records from NIROS are processed by the NISRA Vital Statistics Unit. Provisional data on deaths registered in each week (ending on a Friday) are compiled at the end of the following week. The data presented here is based on registrations of deaths, not occurrences. The majority of deaths are registered within five days in NI. COVID-19 deaths include any death where Coronavirus or Covid-19 (suspected or confirmed) was mentioned anywhere on the death certificate. These figures may be impacted by General Registration Office closures over public holidays.

5.7 Excess mortality surveillance

PHA reports the weekly number of excess deaths from any cause in NI using the Mortality Monitoring in Europe (EuroMOMO) model. EuroMOMO provides a coordinated, timely and standardised approach to monitoring and analysing mortality data across the UK and Europe. Based on mortality data supplied by NISRA, the EuroMOMO model produces the number of expected and observed deaths every week, corrected for reporting delay and standardised for the population by age group and region. Excess mortality is defined as a statistically significant increase in the number of deaths reported over the expected number for a given point in time. Results are provisional due to the time delay in deaths registration. The method was updated in week 13, 2022 in consideration of the pandemic years.

6.1 Episodes by Epidemiological Week

6.2 Weekly Episode rate by Local Government District, over a six week period

6.3 Weekly Episode rate by age group, over a six week period