All AstraZeneca vaccination clinics planned for today have been cancelled.
It comes after the National Immunisation Advisory Committee (NIAC) said the jab should not be offered to people aged under 60.
The committee made the recommendation after the European Medicines Agency (EMA) concluded that blood clots should be listed as one of the “very rare side effects” of the vaccine.
The agency said that noted that the benefits of the jab continue to outweigh the risk.
It noted that it had examined a total of 86 reported cases out of around 25 million vaccinated people.
In the UK meanwhile, Health Secretary Matt Hancock has pointed out that people are more likely to develop blood clots from long-haul plane travel than from the vaccine.
Speaking last night, NIAC Chair Professor Karina Butler said anyone offered AstraZeneca in the coming weeks should know that it is safe and effective.
“People should be absolutely confident that that is the very best thing for them to do and that any risk associated with the vaccine is really infinitesimal compared to the risks from COVID,” she said.
She noted that someone aged over 60 is almost 100 times more likely to die from COVID than from getting the AstraZeneca vaccine.
The acting Chief Medical Officer Dr Ronan Glynn said the extent of the impact the recommendation will have on vaccine rollout in Ireland “remains to be seen.”
“The HSE will be looking at how to effectively reallocate vaccine,” he said.
“So, it is not necessarily the case that this will have a material impact or delay on the rollout of the programme at a population level but I think, in fairness, we need to give the HSE at least a couple of days to model the impact of this.”
He said he would “highly, strongly recommend” that anyone over-60 takes the vaccine when it is offered to them.
“What they are being offered is a very safe, very effective vaccine for their age cohort and, as we have shown, the risks to them of contracting COVID-19, ending up in critical care, ending up dying as a result of that disease are far, far, far higher than any potential risk from receipt of one of these vaccines.”
Under the new NIAC guidelines, people under 60 with an underlying health condition that have already received their first dose should get their second after 12 weeks as scheduled.
Those without an underlying condition will have their second dose pushed back to 16 weeks, “to allow for further assessment of the benefits and risks as more evidence becomes available.”
As of Saturday, 1,058,394 vaccine doses had been administered in Ireland.
Some 745,363 people had received their first dose, while 313,031 people had received both doses.