The portal to register for a covid-19 vaccine will open to people aged 45 to 49 this week.
49-year-olds can register for an appointment from tomorrow, with those aged 48 to register on Thursday, and so on.
More than 2.1 million vaccine doses have now been administered in the Republic.
People can register for their vaccine by going to vaccine.HSE.ie or calling 1850 24 1850.
It comes as some employers are forcing workers to take unpaid leave to attend vaccination appointments.
The Government is calling on business owners to be flexible, as a vaccinated workforce will greatly assist the economy.
SIPTU wants employers to offer two hours paid leave for people to get the vaccine, should their appointment fall during working hours.