The Government will have "more options" for reopening society once people over the age of 70 have received their Covid-19 vaccines, the head of the health service has said.
Paul Reid said the over-70s should be fully vaccinated by mid-May and that the next priority groups should start receiving their first coronavirus jabs in April and May.
Monday saw the rollout of the national vaccination programme for people aged 85 and over officially get under way across the country.
The jabs will be administered at local GP practices and at 37 vaccination centres over the next three weeks.
Stocks of vaccine were delivered to about 84 GP practices today, according to the Irish College of General Practitioners (ICGP).
The majority of GPs are expected to start vaccinating patients from tomorrow onwards.
The HSE has said some 13,500 people over the age of 85 are due to receive their first dose of either the Pfizer BioNTech or Moderna vaccine by the end of the week.
All those over 70 are scheduled to have received their first dose by mid-April and their second dose by mid-May.
It comes as the vaccination programme continues among care homes and frontline healthcare workers.
On Sunday about 5,000 GPs and practice nurses received the jab at vaccination centres across the country.
HSE chief executive Mr Reid told Newstalk it is a very important week for the rollout of the programme, with a "significant" extra delivery of the vaccines allowing greater numbers of healthcare workers be vaccinated.
In total, more than 80,000 doses are due to be administered this week, including staff and residents in long-term care facilities and frontline health workers.
Mr Reid said once residents of long-term care facilities, healthcare workers and people over the age of 70 are fully vaccinated, the landscape will start to change.
"It gives Government more options because at that stage we'll be protecting the most vulnerable," he said.
"The people who we know have suffered the most in terms of mortality."
Mr Reid said the three main suppliers of vaccines have committed to supplying about 1.24 million doses by the end of March.
"That's largely a function of some improvement from the AstraZeneca delivery," he said.
"That starts to address the cohort one - around 92,000 people in long-term care facilities, residents and staff; frontline healthcare workers - there's about 175,000; and then there's almost half a million people in the 70-plus age cohort. It starts to address all of those.
"After that, the next cohort would be healthcare workers not in direct patient contact, and then 65 to 69-year-olds with vulnerable conditions."
The vaccination of healthcare workers not in direct patient contact and those aged between 65 and 69 years is scheduled to get under way in April and May.
Dr Nuala O'Connor, the ICGP's clinical lead on Covid-19, described the rollout of the vaccine for the over-85s as a "historic moment".
"GPs look forward to vaccinating this cohort of patients, who are particularly vulnerable to Covid-19," she said.
"This is a major exercise in vaccine delivery but we are very confident general practice can deliver safely and effectively."
Patients are urged to wait to hear from their GP for their appointment time.
Health Minister Stephen Donnelly today confirmed details of 37 vaccination centres across Ireland, which will be used for the rollout of the vaccines in the community. There will be five centres in Cork; at City Hall, Páirc Uí Chaoimh, MTU Campus Melbourn Building, Bantry PCC and Mallow GAA Club.
While currently vaccines are being administered in healthcare settings and by GPs, many people in the coming weeks and months will be offered their vaccination in these centres, having registered online.
Mr Donnelly said people can expect to see these vaccination centres "ready and waiting in their county".
"We have always said the vaccination programme would only be limited by the availability and reliability of supply in these early stages of the programme," he said.
"In the coming months supply will increase substantially and we will see these centres operating to full capacity and administering vaccines to the general population, following the Government priority list."
As of Friday, a total of 265,237 vaccine doses had been administered in Ireland.
Some 175,238 have received their first dose, while almost 90,000 people are fully vaccinated.