The vaccines are being administered today.
Inoculations will get underway today at Cork University Hospital, Beaumont Hospital and St James's Hospital in Dublin, and at Galway University Hospital, where a small number of people will receive the vaccines ahead of Monday's roll-out to nursing homes.
A 79-year-old Dublin grandmother named Annie, an ICU nurse and a junior doctor are among those who will receive the vaccines today.
The vaccine is being allocated to people in a provisional order.
Frontline workers and people aged 65 years and older who are residents of long-term care facilities will be the first to get the jab.
After that, it will be people over 70 and other healthcare workers not in direct patient contact.
People aged 65-69 and other key workers such as teachers will follow.
A full list is available from the Department of Health.
Professor Brian McCraith, the head of the government's vaccine taskforce, said all nursing homes should be done by the end of February.
He added anyone in Ireland who wants a vaccine will in a best-case scenario receive it by August: "It'll be down to the manufacturing success of the companies, the delivery schedules... But certainly, if all things come to pass, one would be looking at that [August]."
The vaccine first arrived in Ireland on December 26.
While other countries in Europe have begun vaccinating, Ireland has not.
Dr Colm Henry from the HSE has said the vaccine rollout was not a question of speed, but a question of safety.
Tánaiste Leo Varadkar added that the pace at which the vaccination programme will be rolled out is because of issues such as training for vaccinators and informed consent.
Yes. Even if you have had Covid-19, you still need to be vaccinated. This is because you could become infected with the virus again.
It is not, but the HSE has strongly recommended that you get the vaccine as soon as it is available to you.
Your vaccinator - the person who administers the vaccine - will be a trained healthcare professional and will be able to answer any questions you have.
You will get the vaccine as an injection in your upper arm.
You will need 2 doses, at least 21 days apart.
The HSE has said that like all medicines, vaccines can cause side effects.
Most of these are mild to moderate and short-term and not everyone gets side effects.
Common side effects include tenderness, swelling or redness in your arm where you have had the vaccine injection; headache and muscle pain.
The HSE stressed that the Covid-19 vaccine has gone through the same clinical trials and safety checks as all other licensed vaccines.
It added: “But the vaccine is new and long-term side effect information is limited.
“As more people in Ireland and around the world get this vaccine, more information on side effects may become available.”
The Pfizer/BioNTech vaccine is being administered today and going forward.
The European Medicines Agency (EMA) is to issue its verdict on approving the Moderna vaccine on January 6, with a rollout to follow if approved. The Oxford University-AstraZeneca vaccine is also expected to get approval in January.