Ireland suspended the use of the AstraZeneca vaccine on Sunday morning after reports of blood clots in other parts of Europe.
The decision by the NIAC means that many Irish people who were expected to get the jab this week - 30,000 to be exact - will not not receive the shot.
The HSE has said that instead of the scheduled 80,000 doses, the target for this week is 50,000.
Thousands of people with underlying conditions will no longer receive their first shot of the vaccine this week while the remaining healthcare workers are also amongst those affected.
But who will get these jabs? Here's how it stands on the roll-out front and who is next in line to get the vaccine.
List of those still to get the vaccine
Group 5 are people aged 65-69 whose underlying condition puts them at a high risk of severe disease and death.
Group 6 will see people aged 65-69, other healthcare workers, and key vaccination programme workers receive the vaccine.
Group 7 are people between 16-64 and at high risk of severe Covid-19 disease.
Residents of long-term care facilities aged 18-64 are in group 8.
People aged 18-64 years living working in crowded accommodation where self-isolation and social distancing is difficult to maintain make up group 9.
Key workers in essential jobs who cannot avoid a high risk of exposure to Covid-19 will begin to receive vaccinations when group 10 get to the top of the list.
Group 11 will see people essential to education and who face disease exposure receive their vaccination.
Group 12 will see people aged 55-64 years get the vaccine, while group 13 will see people in occupations important to the functioning of society get their jabs.
Citizens aged 18-54 years who did not have access to the vaccine in prior phases will receive them in group 14.
Children, adolescents up to 18 years and pregnant women (to be refined) are the last on the list to be vaccinated, in group 15.
