The Health Service Executive has urged people in at-risk groups to get vaccinated against the flu before the winter sets in.
The call comes as a Europe-wide study indicated that up to 1,000 people in Ireland could die of complications arising from the virus this winter.
The uptake among people over 65 last season was almost 57%, less than the 75% target set by the World Health Organisation.
The vaccine is strongly recommended for everyone over 65, for those with long-term medical conditions, all pregnant women, healthcare workers and carers of those in at-risk groups.
Speaking on RTÉ's Morning Ireland, Head of HSE National Immunisation Office Dr Brenda Corcoran said the vaccine is up to 90% effective.
She said: "The only people who should not get vaccinated are those who have had a serious allergic reaction to a previous dose."
Dr Corcoran added that research has shown if people get the flu there is an increased risk of heart attack and stroke.
It is free to everyone in at-risk groups and is available for adults in both pharmacies and medical surgeries.
Children can only be vaccinated by a doctor.
Asked whether it was necessary to get a new vaccine every year, Dr Corcoran said: "You need to get the vaccine every year, because every year there are new strains in the vaccine.
"We haven't seen any flu in Ireland or Europe yet. Flu is highly unpredictable so we don't know if we're going to get a mild season or a very severe season. But we do know the vaccine works."