There were up to 2,300 excess deaths between March 2020 and February 2021 compared to previous years, according to an analysis of death notices by the Central Statistics Office.
Researchers examined 30,000 death notices on the RIP.ie website over that period with the data showing a range of estimates for excess deaths between 2,034 and 2,338.
The first reported death due to Covid-19 in Ireland was on 11 March, 2020.
Excess mortality measures the number of deaths over and above what would be expected under normal circumstances.
In figures released this morning, the CSO said there were pronounced increases in the number of death notices observed in April 2020 and in January and February 2021 compared to the same months in 2017, 2018 and 2019.
CSO Statistician, John Flanagan, said "the number of death notices increased to 3,504 in April 2020 from 2,864 in March 2020".
He added: "In comparison, the average number of registered deaths for April for the years 2014-2018 was approximately 2,500."
The data also shows that in April 2020 and January and February 2021 there were significant increases in death notices which mentioned older persons' facilities as the place of death.
There was also an increase in the number of death notices related to hospitals which peaked at 1,241 in January 2021.
The CSO also noted that the Health Protection Surveillance Centre reported that no influenza, RSV or acute respiratory infection (ARI - excluding Covid-19) outbreaks were notified to HPSC during the 2020/2021 season to date.