What's going around in Ireland?

The Health Protection Surveillance Centre combines sentinel GP consultations, sentinel-laboratory positivity, hospital and ICU admissions, and variant characterisation at the National Virus Reference Laboratory into a weekly Respiratory Viruses Report covering flu, SARS-CoV-2, and RSV. The same indicators feed ECDC ERVISS. On infectrisk.com we condense this picture into a qualitative low/moderate/high classification.

“Tripledemic” is a media term for the simultaneous winter circulation of flu, COVID-19, and RSV first widely discussed during the 2022–2023 season. Ireland saw clear co-circulation of all three pathogens that winter, with notable pressure on paediatric wards from RSV and on adult critical care from flu and COVID-19. Co-circulation has recurred each winter since, though the relative intensity of each pathogen varies.

The drivers are consistent across temperate Atlantic Europe. Many respiratory viruses remain stable longer in cold, damp indoor air, and heated indoor environments reduce humidity in ways that weaken airway defence. People mix indoors more during Irish winters, schools amplify transmission among children, and end-of-year gatherings accelerate spread. Immunity to seasonal strains is also typically at its lowest as exposure rises.

HPSC uses thresholds derived from historical reference data. Current indicators (sentinel consultations, laboratory positivity, hospitalisations, ICU admissions) are compared against baselines from past non-epidemic weeks and against reference points from severe past seasons. When several indicators cross into elevated ranges at the same time, the weekly Respiratory Viruses Report flags activity as high. Ireland's ERVISS contribution uses the same framework for cross-country comparison.

Ireland's winter respiratory burden often tracks closely with the UK given similar climate, travel patterns, and demographic structure, though the UK is reported separately from ERVISS through its own UKHSA channels. Within the EU, Ireland's curve can be read alongside France, the Netherlands, and other western European neighbours through ECDC's dashboards. Lead–lag patterns between Ireland and neighbours are typically a matter of weeks.