The Health Products Regulatory Authority (HPRA) has been notified of approximately 2,800 reports of suspected side effects associated with the AstraZeneca vaccine.
In a statement, the HPRA said that of 204,270 Astrazeneca doses administered, there were 18 reports describing "blood clots or events possibly associated with blood clots."
However, an HPRA review has confirmed that none of the clots reported are of the nature of the very rare blood clots of concern - ie: cerebral venous sinus thrombosis or splanchnic vein thrombosis or blood clots in combination with low platelets.
A small number of additional cases that describe low platelet counts have been received, the HPRA has said, and a follow-up is ongoing to rule out the presence of blood clots.
The HPRA has highlighted the importance of reporting suspected side effects from vaccines through the Covid-19 vaccine adverse reaction report.
"The reporting rate across all Covid-19 vaccines to the HPRA demonstrates that health care professionals and members of the public are actively reporting suspected side effects, with the rate comparable to other EEA countries," it said.
"As for all vaccines, it is possible to experience side effects, the majority of which are known to be mild to moderate.
"Covid-19 is a disease itself associated with blood clotting, as well as risk of hospitalisation and death," the HPRA added.
The HPRA has said it will continue to participate at the European Medicines Agency (EMA) and engage with the National Immunisation Advisory Committee (NIAC) as well as the Department of Health on this matter.
The European Medicines Agency (EMA) said today that unusual blood clots with low blood platelets should be listed as rare side effects of the AstraZeneca vaccine.
The benefits of the vaccine in fighting Covid-19 are still seen to outweigh the risks, according to the EMA’s safety assessment committee PRAC.
The vaccine is now known as Vaxzevria, a brand name-change confirmed this week.
In a statement, the EMA said they carried out a review of 62 cases of cerebral venous sinus thrombosis and 24 cases of splanchnic vein thrombosis reported in the EU drug safety database as of 22 March and noted that 18 of which were fatal.
The cases came mainly from spontaneous reporting systems in the EEA and the UK.
This includes about 25 million people who have received the vaccine.
They said: “EMA’s safety committee (PRAC) has concluded today that unusual blood clots with low blood platelets should be listed as very rare side effects of Vaxzevria (formerly Covid-19 Vaccine AstraZeneca).
"EMA is reminding healthcare professionals and people receiving the vaccine to remain aware of the possibility of very rare cases of blood clots combined with low levels of blood platelets occurring within 2 weeks of vaccination.
So far, most of the cases reported have occurred in women under 60 years of age within 2 weeks of vaccination. Based on the currently available evidence, specific risk factors have not been confirmed.”
The EMA statement continued, "Covid-19 is associated with a risk of hospitalisation and death. The reported combination of blood clots and low blood platelets is very rare, and the overall benefits of the vaccine in preventing Covid-19 outweigh the risks of side effects."
And the EMA advised that national authorities may provide additional guidance on the roll out of the vaccine based on individual situations.