Taoiseach Micheál Martin has said it's going to take "quite a long time to get everybody vaccinated" against COVID-19.
He said it's likely to be March, April or May until 'increased volumes' of vaccines are available.
He said he also shares the Chief Medical Officer's concerns over the recent virus numbers and incidence rate, after yesterday saw a notable jump in the number of new cases.
EU regulators are expected to decide whether to approve the Pfizer / BioNTech vaccine by the end of the month, with a decision on the Moderna vaccine in January.
Speaking on The Hard Shoulder this evening, the Taoiseach said restrictions will still be needed once the first people in Ireland receive a jab.
He said: "The vaccine's arrival gives us a sense we can get through this.
"Certainly it will be seen as an additional tool. We will still have to continue the restrictions in terms of our personal behaviours.
"It's going to take time to roll out a vaccine, so that's why our behaviour is critical."
In terms of a vaccine rollout, the Taoiseach reiterated that the Government will be prioritising nursing home residents and staff, as well as frontline healthcare workers.
Mr Martin said he felt it was important to lift level five after six weeks as promised, and that people and businesses did need the lead-up to Christmas.
However, he said the recent increase in COVID-19 case numbers is a concern for the Government.
The Taoiseach said: "I think we all have to watch our behaviour over the next seven days.
"We all want to be meet our loved ones over Christmas... for those who want to meet their grandparents and parents, how you behave in the next seven to ten days is crucial to ensure that's a healthy meeting.
"We need to reduce our social contacts, and behave as if we have the virus. People have to wear masks in crowded situations... keep their social distance... and reduce their contacts.
"Obviously, there will be a lot more movement in advance of Christmas Day - that's where the danger lies, and we'll be keeping a very close eye on the numbers from here on."
In terms of the prospect of a third lockdown, he acknowledged that people are fed up of the virus and the associated restrictions.
He said the Government will look at the situation in January, and any further restrictions would be informed by research, data and consultation with NPHET.