Severe acute respiratory infections (SARI) surveillance report, Ireland
Weekly Report on Severe Acute Respiratory Infections (SARI), Ireland
Week 40 2025 (week ending 05/10/2025)
Report prepared on 08/10/2025
1 About this report
Three sentinel hospital sites participate in the severe acute respiratory infections (SARI) surveillance programme in Ireland. St Vincent’s University Hospital (SVUH) commenced SARI surveillance on 5th July 2021, and St James’s Hospital (SJH) and University Hospital Limerick (UHL, paediatric cases only) commenced SARI surveillance on 30th September 2024 (Week 40 2024).
Data were extracted from the HPSC SARI surveillance database on 08/10/2025. Data are provisional and subject to ongoing review, validation and update. As a result, figures presented in this report may differ from previously published figures.
Three of the three SARI sentinel hospital sites (100%) reported data for the current week (W40 2025). Variations in the number of sentinel sites reporting each week, should be considered when comparing incidence rates and case numbers from previous weeks.
2 Key message
Based on data from all three sentinel hospital sites, SARI activity remains low; 57 SARI cases were admitted in week 40, a 12.3% decrease on the 65 cases admitted in week 39 2025.
SARS CoV-2 positivity remained stable and at low levels 9.5% (W39) and 9.3% (W40). RSV positivity decreased from 1.6% (W39) to 0% (W40) and no cases tested positive for influenza in weeks 39 and 40 2025.
3 Summary
SARI case numbers and incidence:
57 SARI cases were admitted to three SARI sentinel sites in week 40 2025, compared to 65 cases from three sites in week 39 2025 (12.3% decrease).
SARI cases <15 years: 15 cases in week 40 2025 compared to 19 in week 39 2025 (21.1% decrease)
SARI cases ≥15 years: 42 cases in week 40 2025 compared to 46 in week 39 2025 (8.7% decrease)
The incidence rates per 1,000 emergency department admissions were as follows:
All SARI cases: 73.2 in week 40 2025, compared to 86.4 in week 39 2025 (15.3% decrease).
SARI cases <15 years: 263.2 in week 40 2025, compared to 339.3 in week 39 2025 (22.4% decrease).
SARI cases ≥15 years: 58.2 in week 40 2025, compared to 66.1 in week 39 2025 (12.0% decrease).
Age profile (W40 2025): 50.9% (n=29) cases were aged ≥65 years and 19.3% (n=11) cases aged <5 years:
All SARI cases: median age 65 years; IQR: 9-77 years.
SARI cases <15 years: median age 2 years, IQR: 0-5 years.
SARI cases ≥15 years: median age 72 years, IQR: 58-80 years.
Virus positivity rate among SARI cases (W40 2025): Among those tested (94.7%, n=54):
9.3% (n=5) tested positive for SARS-CoV-2, compared to 9.5% (n=6) in week 39 2025. Among SARI cases aged <15 years 13.3% (n=2) tested positive for SARS CoV-2 and 7.1% (n=3) tested positive among SARI cases aged ≥15 years in week 40 2025
No cases tested positive for influenza in weeks 39 and 40 2025
No cases tested positive for RSV, compared to 1.6% (n=1) in week 39 2025.
Genomic surveillance (W21 2025-W40 2025): Among SARI SARS-CoV-2 positive specimens sequenced (n=40), XFG variant was the dominant variant at 62.5% (n=25), followed by LP.8.1 variant, at 12.5% (n=5).
Influenza and RSV typing/subtyping (W21 2025-W40 2025):
For cases admitted since week 21 2025, influenza A is the predominant virus circulating amongst influenza positive SARI cases at 44.4% (n=4)
Underlying medical conditions (W40 2025): 70.2% (n=40) of SARI cases reported at least one underlying medical condition; among those <15 years 20.0% (n=3) and among those aged ≥15 years 88.1% (n=37) of cases reported at least one underlying medical condition.
Severe outcomes (W21 2025-W40 2025)
2.8% (n=21) of SARI cases were admitted to ICU. The median length of stay was 5 days, IQR 3-7 days (Table 8). Among SARI cases admitted to ICU, none tested positive for SARS CoV-2, influenza or RSV.
3.8% (n=32) of SARI cases died in hospital. The median age was 78 years, IQR 73-86.25 years, 90.6% (n=29) were ≥65 years of age
Vaccination status (W21 2025-W39 2025)
- Amongst SARI cases positive for SARS CoV-2, aged ≥6 months and with known vaccination status, (n=78), 91% (n=71) had NOT received a COVID-19 vaccine dose in the six months prior to the reported episode of illness (Table 9).
4 SARI case numbers and incidence rates
4.1 SARI cases by site
Figure 4.1: Number of SARI cases by sentinel hospital site and by week of admission W21 2025-W40 2025 (n=841)
4.2 SARI cases by age group
Figure 4.2: Number of SARI cases by age group and week of admission W21 2025-W40 2025
4.3 Incidence admissions
Figure 4.3: SARI age-specific incidence rates per 1,000 hospital admissions via emergency departments by week of admission W21 2025-W40 2025
NOTE: SARI cases are recruited from emergency department admissions only in SVUH, SJH and UHL.
4.4 Incidence (All seasons)
Figure 4.4: SARI incidence rates per 1,000 ED admissions by week of admission between weeks 40 to 39
NOTE: In seasons 2021/2022, 2022/2023 & 2023/2024 one hospital site (SVUH) participated in SARI surveillance. In the 2024/2025 & 2025/2026 season three hospital sites (SVUH, SJH & UHL) participated
5 Demographics
Table 1: Number and proportion of SARI cases by sex and age, for the current week (W40 2025), last four weeks (W37 2025-W40 2025) and W21 2025-W40 2025
Current week | Last four weeks | Total | ||
|---|---|---|---|---|
| W40 2025 | W37 2025-W40 2025 | W21 2025-W40 2025 | |
Characteristic | Category | N = 57 | N = 232 | N = 850 |
Gender | Female | 29 (50.9) | 120 (51.7) | 412 (48.5) |
Male | 28 (49.1) | 112 (48.3) | 438 (51.5) | |
Age <15 years (in years) | Median (IQR) | 2 (0 - 5) | 2 (1 - 5) | 2 (1 - 5) |
Range | 0 - 9 | 0 - 13 | 0 - 14 | |
Age ≥15 years (in years) | Median (IQR) | 72 (58 - 80) | 72 (61 - 80) | 73 (62 - 81) |
Range | 26 - 93 | 20 - 97 | 16 - 97 | |
Age groups (years) | <1 | 6 (10.5) | 15 (6.5) | 56 (6.6) |
1-4 | 5 (8.8) | 32 (13.8) | 109 (12.8) | |
5-14 | 4 (7.0) | 17 (7.3) | 66 (7.8) | |
15-34 | 2 (3.5) | 8 (3.4) | 23 (2.7) | |
35-64 | 11 (19.3) | 45 (19.4) | 154 (18.1) | |
65-79 | 17 (29.8) | 68 (29.3) | 259 (30.5) | |
80+ | 12 (21.1) | 47 (20.3) | 183 (21.5) | |
6 PCR testing for SARS-CoV-2, Influenza and RSV
SARI cases are tested, on-site in each hospital, by PCR for SARS-CoV-2, influenza and RSV on admission.
Table 2: Number and proportion of SARI cases PCR positive for SARS-CoV-2, influenza, and RSV for the current week, last four weeks (W37 2025-W40 2025) and W21 2025-W40 2025
| Current week | Last four weeks | Total | |||
|---|---|---|---|---|---|---|
| W40 2025 | W37 2025-W40 2025 | W21 2025-W40 2025 | |||
| <15y | ≥15y | <15y | ≥15y | <15y | ≥15y |
SARS-CoV-2 | 2 (14.3) | 3 (7.5) | 8 (12.9) | 15 (9.3) | 34 (15.2) | 70 (12.6) |
Influenza | 0 (0.0) | 0 (0.0) | 1 (1.6) | 0 (0.0) | 2 (0.9) | 7 (1.3) |
RSV | 0 (0.0) | 0 (0.0) | 1 (1.6) | 0 (0.0) | 2 (0.9) | 1 (0.2) |
1n (%) | ||||||
Note: During W21 2025-W40 2025 1 SARI case was coinfected with more than one of the three viruses under surveillance.
A further breakdown of SARI positivity by hospital site is available in the Appendix.
6.1 Number PCR positive
Figure 6.1: Number of SARI cases PCR positive for SARS-CoV-2, influenza and RSV by week of admission W21 2025-W40 2025
6.2 Percentage PCR positive
Figure 6.2: Percentage of SARI cases PCR positive for SARS-CoV-2, influenza, RSV and overall positivity by week of admission W21 2025-W40 2025
6.3 Percentage PCR positive by age group
Figure 6.3: Weekly positivity rate of SARI cases PCR positive for SARS-CoV-2, influenza and RSV by age group and by week of admission W21 2025-W40 2025
Note: Y-axis scale may differ for each age group
7 SARS-CoV-2 genomic analysis
Note: There is typically a lag time of at least 3 weeks between a case being admitted, positive samples selected for sequencing and sequencing being completed and reported.
For further information on circulating variants in Ireland, see Respiratory virus notification data hub - Health Protection Surveillance Centre (hpsc.ie) and Integrated Respiratory Virus Bulletin.
Table 3: Number and proportion of SARS CoV-2 positive SARI cases sequenced and reported by Pango lineage and variant W21 2025-W40 2025
Variant | n | % | Pango Lineage | n | % |
|---|---|---|---|---|---|
XFG | 25 | 62.5 | XFG | 9 | 22.5 |
XFG.2 | 2 | 5.0 | |||
XFG.22.1 | 1 | 2.5 | |||
XFG.3 | 9 | 22.5 | |||
XFG.3.1 | 1 | 2.5 | |||
XFG.3.10 | 1 | 2.5 | |||
XFG.3.8 | 1 | 2.5 | |||
XFG.5 | 1 | 2.5 | |||
LP.8.1 | 5 | 12.5 | LP.8.1.1 | 1 | 2.5 |
LP.8.1.9 | 1 | 2.5 | |||
PF.1 | 1 | 2.5 | |||
PF.2 | 1 | 2.5 | |||
PR.2 | 1 | 2.5 | |||
NB.1.8.1 | 5 | 12.5 | NB.1.8.1 | 3 | 7.5 |
PQ.1 | 1 | 2.5 | |||
PQ.4 | 1 | 2.5 | |||
BA.2.86 | 3 | 7.5 | NL.22.1 | 1 | 2.5 |
PY.1 | 1 | 2.5 | |||
XFC | 1 | 2.5 | |||
XEC | 2 | 5.0 | XEC.4 | 1 | 2.5 |
XFN | 1 | 2.5 | |||
Total | 40 | 100.0 | - | 40 | 100.0 |
7.1 SARS-CoV-2 variants by week
Figure 7.1: Number of SARS CoV-2 positive SARI cases sequenced, by variant and by week of hospital admission, W21 2025-W40 2025 (n=104)
*Includes sub-lineage JN.1, excludes lineage KP.3
**Sample either not suitable for sequencing, or result is pending
7.2 SARS-CoV-2 variants season to date
Figure 7.2: Proportion of SARS CoV-2 positive SARI cases sequenced, W21 2025-W40 2025 (n=40)
*Includes sub-lineage JN.1, excludes lineage KP.3
8 Influenza typing/subtyping
8.1 Influenza subtyping by week
Figure 8.1: Number of influenza positive SARI cases by influenza type/subtype and by week of admission, W21 2025-W40 2025 (n=9)
8.2 Influenza subtyping (all age groups)
Figure 8.2: Proportion of influenza positive SARI cases by type/subtype, W21 2025-W40 2025 (n=9)
8.3 Influenza subtyping (<15 years and ≥15 years)
Figure 8.3: Proportion of influenza positive SARI cases by type/subtype among those aged <15 years (n=2) and ≥15 years (n=7) W21 2025-W40 2025
9 RSV typing
9.1 RSV typing by week
Figure 9.1: Number of RSV positive SARI cases by RSV type and by week of admission, W21 2025-W40 2025 (n=3)
10 Symptoms
Table 4: Number and proportion of SARI cases’ clinical symptoms, either at or prior to hospital admission, for the last four weeks (W37 2025-W40 2025), and W21 2025-W40 2025
Last four weeks | Total | |||
|---|---|---|---|---|
W37 2025-W40 2025 | W21 2025-W40 2025 | |||
Clinical symptoms | <15y | ≥15y | <15y | ≥15y |
Cough | 47 (73.4) | 145 (86.3) | 151 (65.4) | 524 (84.7) |
Shortness of breath | 22 (34.4) | 149 (88.7) | 66 (28.6) | 536 (86.6) |
Fever | 44 (68.8) | 88 (52.4) | 182 (78.8) | 337 (54.4) |
General deterioration | 0 (0.0) | 59 (35.1) | 0 (0.0) | 248 (40.1) |
Malaise | 20 (31.3) | 33 (19.6) | 68 (29.4) | 104 (16.8) |
Nausea/Vomiting | 17 (26.6) | 22 (13.1) | 69 (29.9) | 78 (12.6) |
Sore throat | 28 (43.8) | 8 (4.8) | 94 (40.7) | 42 (6.8) |
Acute confusion | 0 (0.0) | 16 (9.5) | 0 (0.0) | 67 (10.8) |
Diarrhoea | 4 (6.3) | 12 (7.1) | 16 (6.9) | 37 (6.0) |
Muscular pain | 0 (0.0) | 7 (4.2) | 0 (0.0) | 51 (8.2) |
Headache | 3 (4.7) | 12 (7.1) | 9 (3.9) | 37 (6.0) |
Increased work of breathing | 32 (50.0) | 0 (0.0) | 32 (13.9) | 0 (0.0) |
Coryza | 15 (23.4) | 0 (0.0) | 15 (6.5) | 0 (0.0) |
Sepsis | 2 (3.1) | 2 (1.2) | 3 (1.3) | 8 (1.3) |
Ageusia/Dysgeusia/Anosmia | 1 (1.6) | 1 (0.6) | 1 (0.4) | 1 (0.2) |
Apnoea | 0 (0.0) | 0 (0.0) | 1 (0.4) | 0 (0.0) |
Note: Collection of additional symptoms increased work of breathing and coryza implemented from week 39 2025
11 Underlying medical conditions and risk factors
SARI cases may be reported with one or more underlying medical conditions. Weekly proportions can be based on small numbers and vary from week to week, caution is therefore advised when interpreting changes in weekly proportions (Table 5).
Table 5: Number and proportion of SARI cases with underlying medical conditions reported on hospital admission (among those who reported having underlying medical conditions), for the last four weeks (W37 2025-W40 2025), W21 2025-W40 2025
| Last four weeks | Total | ||
|---|---|---|---|---|
| W37 2025-W40 2025 | W21 2025-W40 2025 | ||
Condition | <15y | ≥15y | <15y | ≥15y |
No underlying medical conditions | 45 (70.3) | 11 (6.5) | 150 (64.9) | 35 (5.7) |
Lung disease | 1 (1.6) | 75 (44.6) | 4 (1.7) | 279 (45.1) |
Heart disease | 3 (4.7) | 61 (36.3) | 8 (3.5) | 260 (42.0) |
Hypertension | 0 (0.0) | 52 (31.0) | 0 (0.0) | 234 (37.8) |
Cancer | 0 (0.0) | 42 (25.0) | 0 (0.0) | 159 (25.7) |
Neurological disease | 1 (1.6) | 30 (17.9) | 15 (6.5) | 123 (19.9) |
Rheumatological disease | 0 (0.0) | 29 (17.3) | 0 (0.0) | 127 (20.5) |
Asthma | 7 (10.9) | 27 (16.1) | 22 (9.5) | 83 (13.4) |
Diabetes | 0 (0.0) | 18 (10.7) | 0 (0.0) | 98 (15.8) |
Immunocompromised | 1 (1.6) | 18 (10.7) | 1 (0.4) | 82 (13.2) |
Dementia | 0 (0.0) | 19 (11.3) | 0 (0.0) | 58 (9.4) |
Kidney disease | 0 (0.0) | 11 (6.5) | 1 (0.4) | 56 (9.0) |
Liver disease | 0 (0.0) | 6 (3.6) | 0 (0.0) | 31 (5.0) |
Obesity | 0 (0.0) | 8 (4.8) | 2 (0.9) | 27 (4.4) |
Intellectual disability | 3 (4.7) | 2 (1.2) | 17 (7.4) | 6 (1.0) |
Down syndrome | 0 (0.0) | 1 (0.6) | 3 (1.3) | 3 (0.5) |
Tuberculosis | 0 (0.0) | 1 (0.6) | 0 (0.0) | 3 (0.5) |
Asplenia | 0 (0.0) | 0 (0.0) | 2 (0.9) | 0 (0.0) |
Cystic fibrosis | 0 (0.0) | 0 (0.0) | 0 (0.0) | 1 (0.2) |
Long COVID | 0 (0.0) | 0 (0.0) | 0 (0.0) | 1 (0.2) |
12 Clinical course and outcome
12.1 Complications
Information on the clinical course during hospitalisation is only available after patient discharge, and there may be a delay between discharge and data collection, due to the manual data collection methods required. Furthermore, data collection is ongoing for those not yet discharged from hospital.
SARI cases could be reported with one or more complications; among those for whom discharge information is available the most common complication reported was pneumonia (Table 6).
Table 6: Number and proportion of SARI cases and complications among discharged SARI cases, for the last four weeks (W37 2025-W40 2025), and W21 2025-W40 2025
| Last four weeks | Total | ||
|---|---|---|---|---|
| W37 2025-W40 2025 | W21 2025-W40 2025 | ||
Complication | <15y | ≥15y | <15y | ≥15y |
No complications | 31 (53.4) | 15 (21.4) | 132 (58.7) | 88 (18.0) |
Pneumonia | 14 (24.1) | 45 (64.3) | 50 (22.2) | 333 (68.0) |
Acute kidney injury | 0 (0.0) | 4 (5.7) | 0 (0.0) | 42 (8.6) |
Bronchiolitis | 10 (17.2) | 0 (0.0) | 39 (17.3) | 1 (0.2) |
Heart failure | 0 (0.0) | 2 (2.9) | 0 (0.0) | 36 (7.3) |
Sepsis | 1 (1.7) | 1 (1.4) | 1 (0.4) | 21 (4.3) |
ARDS | 9 (15.5) | 0 (0.0) | 20 (8.9) | 1 (0.2) |
Secondary bacterial infections | 2 (3.4) | 0 (0.0) | 2 (0.9) | 13 (2.7) |
Multi organ failure | 0 (0.0) | 0 (0.0) | 0 (0.0) | 3 (0.6) |
Other complications | 3 (5.2) | 8 (11.4) | 5 (2.2) | 70 (14.3) |
Note: Collection of additional complications acute atrial fibrillation, acute viral myositis and respiratory complications implemented from week 39 2025.
The following complications have been removed from the table, as there are no cases reporting these conditions in the above time-periods: Myocarditis, Encephalitis, PIMS*, Acute atrial fibrillation, Acute viral myositis, Respiratory complications
*Paediatric inflammatory multisystem syndrome
12.2 Respiratory support
Among SARI cases who have been discharged, the highest level of respiratory support received during hospitalisation is described in Table 7.
Table 7: Number and proportion of SARI cases by highest level of respiratory support received, among discharged SARI cases, for the last four weeks (W37 2025-W40 2025), and W21 2025-W40 2025
Last four weeks | Total | |||
|---|---|---|---|---|
| W37 2025-W40 2025 | W21 2025-W40 2025 | ||
Respiratory support | <15y | ≥15y | <15y | ≥15y |
No respiratory support given | 38 (66%) | 27 (43%) | 160 (71%) | 179 (38%) |
Low-flow oxygen therapy | 12 (21%) | 30 (48%) | 43 (19%) | 205 (43%) |
Non-invasive ventilation | 8 (14%) | 5 (7.9%) | 22 (9.8%) | 87 (18%) |
Invasive ventilation | 0 (0%) | 1 (1.6%) | 0 (0%) | 6 (1.3%) |
1n (%) | ||||
12.3 Severe outcomes
SARI cases are considered to have severe outcomes if they were admitted to ICU and/or died during their hospital stay.
Table 8: Number and proportion of SARI cases with severe outcomes, for the last four weeks (W37 2025-W40 2025), and W21 2025-W40 2025
Last four weeks | Total | |
|---|---|---|
| W37 2025-W40 2025 | W21 2025-W40 2025 |
| N = 232 | N = 850 |
Hospital length of stay (days) | ||
Median (IQR) | 3 (2 - 5) | 4 (2 - 7) |
Range | 1 - 21 | 1 - 109 |
Admitted to ICU, n (%) | 4 (2.5%) | 21 (2.8%) |
ICU length of stay (days) | ||
Median (IQR) | - | 5 (3 - 7) |
Range | - | 1 - 67 |
Died in hospital, n (%) | 3 (1.3%) | 32 (3.8%) |
Note: Paediatric cases from UHL may be reported as admitted to ICU, if transferred to an ICU in a paediatric hospital. However, these cases are excluded from the calculation of length of stay in ICU.
13 Vaccination status
Vaccination data are available approximately one week after cases are notified to HPSC, therefore the vaccination status for the current week’s SARI cases have been excluded from the below analysis.
13.1 COVID-19 vaccination status
During the 2025 summer season (W21 2025-W39 2025) among SARI cases PCR positive for SARS-CoV-2, aged ≥6 months and with known COVID-19 vaccination status (n=78), 91% (n=71) had NOT received a vaccine dose in the six months prior to the reported episode of illness (Table 9).
Table 9: Characteristics of SARI cases positive for SARS-CoV-2 during W21 2025-W39 2025 by time since last COVID-19 vaccine dose
| W21 2025-W39 2025 | ||
|---|---|---|---|
Characteristic | Category | <180 days | ≥180 days |
Gender | Female | 3 (7.9%) | 35 (92.1%) |
Male | 4 (10.0%) | 36 (90.0%) | |
Age (years) | Median (IQR) | 85 (74 - 89) | 73 (51 - 82) |
Range | 49 - 96 | 0 - 93 | |
Age groups (years) | 0-14 | 0 (0.0%) | 15 (100.0%) |
15-59 | 1 (12.5%) | 7 (87.5%) | |
60-69 | 1 (12.5%) | 7 (87.5%) | |
70-79 | 1 (5.0%) | 19 (95.0%) | |
80+ | 4 (14.8%) | 23 (85.2%) | |
Underlying medical conditions | Yes | 7 (10.4%) | 60 (89.6%) |
No | 0 (0.0%) | 11 (100.0%) | |
Unknown | 0 (0.0%) | 0 (0.0%) | |
Patient residence | Residential care facility | 3 (27.3%) | 8 (72.7%) |
Private residence/home | 4 (6.0%) | 63 (94.0%) | |
Other/unknown residence | 0 (0.0%) | 0 (0.0%) | |
Note: Due to small numbers of cases reported as not vaccinated, this group has been included in the ≥180 days group.
Excluded from analysis:
SARS-CoV-2 positive SARI cases with unknown vaccination status, 5 (5.1%) are excluded.
SARS-CoV-2 positive SARI cases aged <6 months, 16 (16.2%) are excluded.
13.2 Influenza vaccination status
Vaccination status of influenza positive SARI cases will be reported when >10 cases are admitted during the current 2025/2026 season.
14 Links to other national respiratory virus reports
Respiratory viruses
COVID-19
15 Appendix
Table A1: Number of SARI cases, number tested and positivity by hospital site for the current week (W40 2025), previous week (W39 2025) and W21 2025-W40 2025
Cases | SARS CoV-2 tested | SARS CoV-2 positive | Influenza & RSV tested | Influenza positive | RSV positive | |
|---|---|---|---|---|---|---|
Site | n | n | n (%) | n | n (%) | n (%) |
W40 2025 | 57 | 54 | 5 (9.3) | 54 | 0 (0) | 0 (0) |
SVUH | 19 | 19 | 3 (15.8) | 19 | 0 (0) | 0 (0) |
SJH | 23 | 21 | 0 (0) | 21 | 0 (0) | 0 (0) |
UHL | 15 | 14 | 2 (14.3) | 14 | 0 (0) | 0 (0) |
W39 2025 | 65 | 63 | 6 (9.5) | 63 | 0 (0) | 1 (1.6) |
SVUH | 23 | 23 | 1 (4.3) | 23 | 0 (0) | 0 (0) |
SJH | 23 | 22 | 4 (18.2) | 22 | 0 (0) | 0 (0) |
UHL | 19 | 18 | 1 (5.6) | 18 | 0 (0) | 1 (5.6) |
W21 2025-W40 2025 | 850 | 780 | 104 (13.3) | 780 | 9 (1.2) | 3 (0.4) |
SVUH | 288 | 280 | 41 (14.6) | 280 | 5 (1.8) | 0 (0) |
SJH | 331 | 276 | 29 (10.5) | 276 | 2 (0.7) | 1 (0.4) |
UHL | 231 | 224 | 34 (15.2) | 224 | 2 (0.9) | 2 (0.9) |
16 Technical Notes
16.1 SARI Surveillance objectives
Severe acute respiratory infection (SARI) is of major relevance to public health worldwide. Surveillance of SARI is essential to monitor the (co-) circulation of respiratory pathogens and to assess disease severity. Data collected as part of SARI surveillance can provide important early warning information in the context of respiratory disease outbreaks and pandemics. SARI data can also be used as a platform to measure vaccine and antiviral effectiveness and impact. The objectives of SARI surveillance are:
To describe the number and incidence of SARI cases by aetiology, time, place and person
To describe and monitor trends, intensity of activity and severity of SARI infections
To identify groups at risk of severe disease
To detect unusual and unexpected events
To assess the SARI burden of disease in the participating hospital
To assess and monitor vaccine effectiveness
16.2 Sentinel hospital SARI surveillance sites
SARI surveillance was implemented in one tertiary care adult hospital, St.Vincent’s University Hospital (SVUH), Dublin on the 5th of July 2021. In September 2024 a second tertiary care adult hospital, St James’s Hospital (SJH), was included, both sites reporting on SARI cases aged 15 years and older.
A third tertiary care hospital, University Hospital Limerick (UHL), reporting on SARI cases aged under 15 years of age only, began surveillance in September 2024.
16.3 Case definition
SARI cases are identified from new admissions, based on clinical symptoms. Patients that develop SARI during their admission are not included.
Clinical SARI case:
The European Centre for Disease Prevention and Control (ECDC) clinical SARI case definition is used for SARI surveillance in Ireland since week 34 2021. The case definition for SARI cases aged <6 months was updated for cases admitted from week 40 2025 to include increased work of breathing and apnoea as relevant symptoms.
SARI case definition: A person hospitalised for at least 24 hours with acute respiratory infection and symptom onset within 14 days prior to hospital admission, with at least one of the following symptoms:
cough
fever
shortness of breath
sudden onset of anosmia, ageusia or dysgeusia
increased work of breathing*
Apnoea*
*for cases aged <6 months
A SARI case refers to an individual patient episode of care
16.4 Denominator data
Weekly denominator data on all-cause hospital admissions, through the Emergency Department are provided by the sentinel hospital sites.
16.5 Laboratory testing
SARS-CoV-2, influenza, and RSV PCR testing is carried out on admission.
SARI samples that are positive for SARS-CoV-2 and have a cycle threshold (Ct) value <25 are referred for whole genome sequencing (WGS). The molecular laboratories in SVUH, SJH and UHL are spoke WGS testing sites as part of the national SARS-CoV-2 WGS surveillance programme, for further information please see Whole Genome Sequencing Programme - Health Protection Surveillance Centre (hpsc.ie). SARI WGS testing is performed on-site at SVUH, SJH and UHL.
Samples that are PCR positive for influenza are sent to the National Virus Reference Laboratory (NVRL) for influenza typing/subtyping/genetic and antigenic characterisation.
Samples that are PCR positive for RSV are sent to the National Virus Reference Laboratory (NVRL) for RSV typing.
16.6 Data collection and reporting
St Vincent’s University Hospital: Clinical data are collected and managed using REDCap electronic data capture tools hosted at University College Dublin. Laboratory data are extracted from APEX, the laboratory information management system (LIMS), using IBM Cognos software hosted at SVUH.
St. James’s Hospital: Clinical data are collected and managed on a specifically adapted electronic form within the patient’s electronic patient record (EPR). Laboratory data are extracted from Telepath LIMS.
University Hospital Limerick: Clinical data are collected manually on the hard copy of the UHL SARI Case Report Form (CRF) and then recorded in the electronic SARI questionnaire on ICNET. Details of laboratory results are obtained from ICNET and are also recorded in the electronic SARI questionnaire on ICNET.
Case-based data are reported by SVUH, SJH and UHL to the HSE Health Protection Surveillance Centre (HPSC) on a weekly basis. Data are also reported by HPSC to ECDC via The European Surveillance System (TESSy) on weekly basis as part of the European SARI surveillance programme.
COVID-19 vaccination data are obtained from the National COVID-19 Vaccination Management System (COVAX) and linked to SARI cases by the HSE-Integrated Information Service (IIS), where data are available.
16.7 Reference dates
Influenza season
The influenza surveillance season runs from week 40 (early October) to week 20 (end of May). During this time, seasonal respiratory viruses usually circulate at higher levels, compared to the summer period (weeks 21 to 39). The seasonal comparisons used in this report refer to the influenza surveillance season.
SARI Surveillance
05/07/2021 (Week 27 2021) – commenced of SARI surveillance at first sentinel hospital site
30/09/2024 (Week 40 2024) - commenced SARI surveillance at the second and third sentinel sites
Vaccination campaigns
27/09/2021 (Week 39 2021) – first COVID-19 booster vaccination campaign commenced
22/04/2022 (Week 16 2022) – second COVID-19 booster vaccination campaign commenced
03/10/2022 (Week 40 2022) – Autumn 2022 COVID-19 booster vaccination campaign commenced
28/04/2023 (Week 17 2023) – Spring 2023 COVID-19 booster vaccination campaign commenced
02/10/2023 (Week 40 2023) – Autumn 2023 COVID-19 booster vaccination campaign commenced
22/04/2024 (Week 17 2024) – Spring 2024 COVID-19 booster vaccination campaign commenced
30/09/2024 (Week 40 2024) – Autumn 2024 influenza & COVID-19 booster vaccination campaign commenced
03/04/2025 (Week 13 2025) – Spring 2025 COVID-19 booster vaccination campaign commenced
15/09/2025 (Week 37 2025) – Autumn 2025 influenza & COVID-19 booster vaccination campaign commenced
Winter respiratory virus seasons
04/10/2021 (Week 40 2021) - start of the 2021/2022 season
03/10/2022 (Week 40 2022) - start of the 2022/2023 season
02/10/2023 (Week 40 2023) - start of the 2023/2024 season
30/09/2024 (Week 40 2024) - start of the 2024/2025 season
29/09/2025 (Week 40 2025) - start of the 2025/2026 season
Week number refers to the week of hospital admission. Weeks are from Monday to Sunday, as per the international ISO week1.
16.8 Vaccination status definitions
For the purposes of SARI surveillance, vaccination status of cases is as follows:
Vaccinated COVID case: A confirmed case of COVID-19 who received any dose of a COVID-19 vaccine, ≥14 days before onset of symptoms.
Unvaccinated COVID-19 case: A confirmed case of COVID-19 who did not receive any dose of a COVID-19 vaccine i.e. was never vaccinated.
Time since vaccination: For a vaccinated COVID-19 case, this is the time between the date of last dose vaccination and the date of symptom onset and categorised as <180 days or ≥180 days since vaccination.
Vaccinated influenza case: A confirmed case of influenza will be considered as vaccinated against influenza if they received one dose of the influenza vaccine as part of the current season’s influenza vaccination campaign ≥14 days before onset of symptoms.
Unvaccinated influenza case: A confirmed case of influenza will be considered as unvaccinated if they did not receive an influenza vaccine as part of the current season’s influenza vaccination campaign or if they were vaccinated after onset of symptoms.
Vaccine status unknown: The SARI patient is reported on the SARI hospital clinical questionnaire as vaccinated, however there is no identifiable linked record of COVID-19 vaccination and/or influenza vaccination on the National Immunisation system. Vaccination status is reported as unknown, until verified on the National Immunisation system.
17 Acknowledgements
Sincere thanks are extended to all those who participate in SARI surveillance, including those in St. Vincent’s University Hospital, St James’s Hospital, University Hospital Limerick, Children’s Hospital Ireland, Crumlin, the UCD Clinical Research Centre and the National Virus Reference Laboratory. Thanks to members of the HSE Integrated Information Services (IIS) for work on the SARI-COVAX data linkages.
This report was produced by the SARI Surveillance Team at HPSC, using R studio software.
Monday to Sunday (ISO week) used as per ECDC/WHO/International reporting protocol.↩︎