The vaccination of 35 to 59-year-olds is set to begin next month.
Under a new timeline published last night, 25 to 34-year-olds will get their first doses of the COVID-19 jab in July.
The vaccination of over-60s and very high-risk people is expected to be 'well advanced' this month.
The guide doesn't say when under-25s will get a jab.
Earlier this week, the Government confirmed vaccine registration will open for those aged 50-59 next week.
HSE CEO Paul Reid said people in that age group will then start getting vaccinated in the next 'two to three weeks'.
Vaccination is set to be carried out in 38 mass vaccination centres, with the last dozen or so of the sites to open over the next two weeks.