The European Medicines Agency has found a possible link between AstraZeneca’s COVID-19 vaccine and unusual blood clots in those who have received the jab.
The Agency's safety committee says "unusual blood clots with low blood platelets should be listed as very rare side effects".
It took into consideration all currently available evidence, including the advice from an ad hoc expert group.
The EMA says people should be 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.
The agency insists the overall benefits of the vaccine in preventing COVID-19 outweigh the risks of side effects.
The latest figures show over 204 thousand AstraZeneca covid-19 vaccines have been administered in the Republic of Ireland.
Ireland's National Immunisation Advisory Committee says it will meet to discuss the findings and consider if any further advice is required.