The Republic of Ireland is temporarily suspending use of the AstraZeneca vaccine after fears over blood clotting.
Deputy Chief Medical Officer Dr Ronan Glynn announced the move on Sunday morning.
He said the decision was taken following a report from the Norwegian Medicines Agency of four new reports of serious blood clotting events in adults after vaccination with AstraZeneca.
The UK's Medicines and Healthcare products Regulatory Agency (MRHA) has reviewed data following use of 11 million doses of the vaccine and recommended no change to its use in the UK's vaccination programme.
Dr Phil Bryan, MHRA Vaccines Safety Lead said "we are keeping this issue under close review but available evidence does not confirm that the vaccine is the cause".
"People should still go and get their Covid-19 vaccine when asked to do so," he said.
Deputy First Minister Michelle O'Neill said she had "sought clarification" from Health Minister Robin Swann about the suspension and what it may mean for Northern Ireland.
"Be assured we will keep the public informed," she said.
Dr Glynn stressed "it has not been concluded that there is any link between the Covid-19 vaccine AstraZeneca and these cases".
"However, acting on the precautionary principle, and pending receipt of further information, the National Immunisation Advisory Committee (NIAC) has recommended the temporary deferral of the Covid-19 vaccine AstraZeneca vaccination programme in Ireland," he said in a statement.
An AstraZeneca spokesperson said "an analysis of our safety data that covers reported cases from more than 17 million doses of vaccine administered has shown no evidence of an increased risk of pulmonary embolism, deep vein thrombosis or thrombocytopenia with Covid-19 Vaccine AstraZeneca".
"In fact, the reported numbers of these types of events for Covid-19 Vaccine AstraZeneca are not greater than the number that would have occurred naturally in the unvaccinated population," the spokesperson said.
“In clinical trials, no trends or patterns were observed with regard to pulmonary embolism, deep vein thrombosis, or events possibly related to thrombocytopenia.
“A careful review of all available safety data including these events is ongoing and AstraZeneca is committed to sharing information without delay. We also note that the European Medicine Agency (EMA) has asked for an assessment of events related to thrombocytopenia from other Covid-19 vaccine manufacturers (per communication 11 March).”
It comes amid ongoing issues as the Republic attempts to source enough coronavirus vaccines for its population.
There have been numerous delays and setbacks in EU member states after group ordering of vaccines failed to materialise, leaving the Republic behind Northern Ireland in its vaccination programme.
Earlier this week the Republic's first-quarter vaccination target reduced to 1.1 million from an initial 1.7 million.
The Irish Government has been urged to engage with counterparts in the UK and US in an attempt to address the problem.
Several other European countries have temporarily suspended AstraZeneca jabs following reports of people suffering blood clots.
The EMA reported one person in Austria was diagnosed with blood clots and died 10 days after vaccination, but it stressed there is "currently no indication that vaccination has caused these conditions".
Another person was admitted to hospital in Austria with pulmonary embolism (blockage in arteries in the lungs) after being vaccinated, while one death involving a blood clot was reported in Denmark.
A 50-year-old man is also thought to have died in Italy from deep vein thrombosis (DVT), while there has been an unconfirmed report of another death in Italy.
Denmark, Norway and Iceland have said they are temporarily halting all AstraZeneca vaccinations to investigate the reports.
Italy also followed Austria, Estonia, Latvia, Luxembourg and Lithuania in banning jabs from one particular batch of one million AstraZeneca vaccines, which was sent to 17 countries, after reports of a death.