A further 1,352 cases of Covid-19 have been reported this afternoon following an "inspiring weekend" for the vaccination programme.
HSE chief Paul Reid said that over 18,000 people availed of the new walk-in vaccination centres over the weekend.
Half of those attending the 26 centres are 16 or 17 years old while 64% are under the age of 20.
According to the latest figures, 2.1 million vaccine doses have been administered in the past six weeks.
Minister for Health, Stephen Donnelly, has said the six millionth dose of Covid-19 vaccine will be administered this week.
He described scenes of people queuing at walk-in clinics in recent days as amazing.
"We're nearly at three-in-four adults with full vaccination. Amazing work by all involved," said Mr Donnelly.
Chief Clinical Officer for the HSE, Dr Colm Henry, says more people turned up to the walk-in centres than expected.
He said the fact that two-thirds of those who attended were aged 19 or under was remarkable.
"It's not just the numbers, it's the enthusiasm and the determination of these people to get vaccinated and it really adds to the extraordinary sense of solidarity that you see in this programme," said Dr Henry.
A leading immunology expert has called for a public information campaign to ensure there is a good uptake of the vaccine among 12-15 year olds.
Registration for this age group is set to open within the next two weeks.
Professor of Immunovirology at UCC, Liam Fanning, says it will be worth informing parents and guardians why they should give consent.
Among the reasons for giving young teens the vaccine are making sure that schools can reopen and stay open in a safe manner and to protect the wider family from getting Covid, said Prof Fanning.
It is understood the Government and health officials have already begun planning for the rollout of a booster campaign.
The booster rollout could get underway within the next two to three months beginning with nursing home residents, healthcare workers and those aged over 80.
"We know that booster shots from the data from Pfizer and Moderna will increase antibody levels and T cell responses to this virus so that can only be a good thing," said Prof Fanning.
"We are all going to receive at least one booster shot anyway and by the time we come into next March or April we will have better scientific data on the longevity of the immune response that we have as a result of the booster shot.
"We may or may not need one the following year."
The Department of Health has said there are currently 177 Covid patients in hospital, an increase of 14 on yesterday.
Of those patients in hospital with Covid-19, 27 are in ICU - up one from Sunday.
The Restaurants Association says it will meet with Government officials on Wednesday, to discuss plans for the further easing of Covid restrictions across the hospitality sector.
The group will meet with representatives from the Department of Tourism and Enterprise as well as a number of state agencies.
Indoor hospitality reopened last week for those who are fully vaccinated or have recovered from the virus in the last six months.
Chief Executive of the Restaurants Association, Adrian Cummins, says they are meeting with officials to discuss how measures are being implemented.
Mr Cummins said it has been difficult to implement the regulations as there are so many involved in the current protocol.
The meeting later this week will seek to identify any issues that have arisen surrounding the protocols and are there any amendments that can be made in order to make them more workable.