It's emerged that four of the six residents who died from influenza at a nursing home in Donegal had been vaccinated against the flu.
Three men and three women died at Nazareth House outside Buncrana between March 22nd and April 2nd.
Eleven people there remain ill with varying degrees of symptoms - and doctors say they have concerns about some of these patients.
The Health Protection Surveillance Centre says unfortunately, this year's flu virus was not ideally matched to the strain of flu which caused the deaths.
Director of the Centre, Doctor Darina O'Flanagan, says another factor was undoubtedly the ages of those who died: