People in their 30s are being encouraged to register for a Covid booster online.
The first appointments for this age-group are available from Wednesday.
Those from 16-29 who received the J&J single-dose booster vaccine will also be eligible to get their booster jabs from that day.
Walk-in centres for over-40s will reopen in several locations tomorrow, including in Kilkenny and Clonmel.
In Kilkenny, the Cilin Hill Conference Centre walk-in clinic will be open from 8.30am to 4.30pm, with the clinic closed for an hour for lunch between 12.30 and 1.30pm
While the clinic at the Clonmel Park Hotel will be open from 12pm to 5pm tomorrow afternoon.
Other clinics around the South-East will then open from Tuesday onwards.
Pharmacies, private clinics, and GPs are also administering vaccines.
"I believe there will be a group that haven't yet decided to have a booster" said Dr Denis McCauley from the Irish Medical Organisation "and I think they're possibly waiting in the wings once again to wait on more information in relation to the variant."
"Can I please reiterate that the best defence that you can have is to have the booster as soon as possible."
