The HSE chief also confirmed Ireland has administered its six millionth vaccine dose.
The HSE has said it will operate walk-in Covid-19 vaccination centres across Ireland again this weekend.
This comes following the "great turnout" of people over the Bank Holiday weekend availing of the service, HSE chief Paul Reid has said.
Speaking at a briefing on Thursday afternoon, the CEO said: "Over 30,000 persons attended at the walk-in centres and over half of those overall for the country hadn't already registered on the [HSE vaccine] portal, which is exactly the target groups we were trying to get to."
He stated that around 85% of those vaccinated at walk-in centres were below the age of 30, and 65% were below the age of 20.
"Our immediate focus continues to be delivering first and second doses to all adults and indeed to those over 16," Reid added.
"Along with this... we have three key priorities: commence the process to the vaccination of 12-15 year olds, develop a scenario plan to administer a booster programme when advised in further detail by Government and... implement some further walk-in facilities for this coming weekend."
Reid said the HSE believes there is "still a further potential" in operating walk-in facilities and as such will offer the service again this Friday, Saturday and Sunday.
"We do feel that last weekend, we will have captured probably most of this opportunity that there is there, but we once again open the facilities to see if there are some further people that we can cover and capture through this process."
During the briefing, Reid also revealed Ireland has administered its six millionth Covid-19 vaccine dose.
Details of the walk-in centres and their operating times can be found on the HSE's website
here.
