Peadar Tóibín (Meath West, Aontú)
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179. To ask the Minister for Health the number of excess deaths in Ireland for each of the past five years. [38010/25]

Jennifer Carroll MacNeill (Dún Laoghaire, Fine Gael)
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The Department of Health does not produce estimates of excess mortality. However, the Department works closely with the HSE-Health Protection Surveillance Centre (HPSC) and other stakeholders to monitor estimates of excess mortality. 

Excess mortality is a term used in epidemiology and public health that refers to the number of deaths from all causes during a period of time, above and beyond what we would have normally expected to see. Excess deaths are typically defined as the difference between the observed number of deaths in a specific time period and the expected number of deaths in the same time period.

A number of different methodologies have been developed internationally to try to estimate levels of excess mortality.  All of these methodologies are statistical techniques to estimate excess mortality based on all-cause mortality data. Different estimation methods vary, for example in the years which are used to estimate a baseline, in how they estimate what is the level of ‘expected’ deaths or if they apply a statistical significance test.  There is therefore no single source of data on estimated excess mortality and different estimates exist. 

The HSE-Health Protection Surveillance Centre (HPSC) receives daily registered deaths data from the General Register Office (GRO) on all deaths from all causes registered in Ireland. These data have been used since 2009 to monitor excess all-cause deaths in Ireland as part of a wider European Mortality Monitoring Project known as EuroMOMO (www.euromomo.eu/). EuroMOMO is a European mortality monitoring activity, aiming to detect and measure excess deaths related to seasonal influenza, pandemics and other public health threats.  EuroMOMO publishes a weekly update of estimates of excess mortality, by age group, for all participating European countries www.euromomo.eu/graphs-and-maps. EuroMOMO is the main indicator of excess mortality used in Ireland.

EuroMOMO publish estimates in the form of z-scores. A z-score is a statistical measure that describes how far away from the mean a given data point is. In this context, if the observed number of deaths is the same as the expected number of deaths, the z-score is 0. The greater distance the observed number of deaths is from the expected number (either above or below), the higher the z-score will be (with either positive or negative sign respectively).

Data on the weekly EuroMOMO z-score for Ireland for the last 5 years from Week 28 2019 to Week 26 2025 is attached and shown in Chart 1 below. This data was published by EuroMOMO during Week 27 2025. Caution is required in interpreting data for the most recent weeks.

A z-score of greater than 2 indicates excess mortality. Weeks where the z-score is less than or equal to 2 are considered to not have any excess mortality and to be within the normal range.

Where the z-score is greater than 2 but less than or equal to 4 it is considered to be low excess; greater than 4 but less than or equal to 7 is considered to be moderate excess; and a z-score of 7 or higher is considered high excess.  During the latest 5 years:

• High estimated excess mortality (above the red line in Chart 1) was recorded in Ireland during six weeks: Weeks 14-16 2020, Weeks 03-04 2021 and Week 52 2022.
• Moderate estimated excess mortality (between the green and red lines in Chart 1) was recorded during eight weeks: Week 17 2020, Week 02 2021, Weeks 05-06 2021, Week 15 2022, Week 51 2022 and Weeks 01-02 2023.
• Low estimated excess mortality (between the blue and green lines in Chart 1) was recorded during an additional 25 weeks over the 5-year period.
• Mortality has either been within or below the ‘normal range’ for all other weeks (below the blue line in Chart 1).

Excess mortality has been observed during periods when influenza viruses circulated at high levels in Ireland, and during certain periods of the COVID-19 pandemic.

It should be noted that for more recent periods, these data are provisional due to the time lag with death registration in Ireland. A country-specific adjustment function was applied to correct for the typical lag in registrations of deaths in Ireland (the legal period for death registration in Ireland is currently three months). Nonetheless, estimates of excess mortality for the most recent weeks are reported with some uncertainty and should be interpreted with caution.

Other estimates of excess mortality in Ireland have also been published by the OECD, WHO, Eurostat, CSO, The Lancet and other researchers.  The Department of Health is actively monitoring and reviewing all available data on mortality as it becomes available to gain a better insight on the underlying mortality trends and factors influencing these.