People in their 30s are set to be able to register for a Covid-19 vaccine next week, according to a NPHET member.
The HSE says it expects registration for 30 to 39 year olds to open online shortly.
Over 3.1 million vaccines have been administered so far - with registration still open for 40 to 69 year olds.
Tony O'Brien, a former director-general of the HSE, is welcoming the latest development.
"Yesterday's news that the over 30s will be able to register on the portal is really positive.
"It will be a really significant milestone, and shows that our vaccine programme is catching up with that in the UK, and this will be very welcome news for everybody.
"Following that age group we'll get to the 20s and then the teens, and that should set us up very well for reopening universities at the start of next term, so it's all very positive."