The HSE has said it will be administering the AstraZeneca vaccine as the second dose vaccination for healthcare workers.
It said it was operating under guidance it received from the National Immunisation Advisory Committee (Niac) last month.
Trade unions had sought clarification after Niac, in a letter which emerged on Thursday, suggested the number of very rare type of blood clots linked to the second doses of the AstraZeneca vaccine was higher than previously understood.
Unions said Niac had opened up whether it would be preferable to give a mRNA vaccine, such as Pfizer or Moderna, as the second dose to people under 50 who had received AstraZeneca as a first dose.
Unions, who represent tens of thousands of healthcare workers who received an initial dose of the AstraZeneca vaccine, sought an urgent meeting with the HSE on Friday.
In a letter to trade unions seen by The Irish Times, HSE chief clinical officer Dr Colm Henry said it was administering second doses of the AstraZeneca vaccine – known technically as Vaxzevria – in accordance with Niac guidance which it received on April 27th.
“We continue to recommend that healthcare workers take the second dose Vaxzevria as offered to them in order to protect them, our patients and the population at large," the letter said.
“Good and timely uptake of the second dose of Vaxzevria will be crucial to ensuring that we continue to provide the maximum protection available to our at-risk population groups, which include our frontline healthcare workers at highest risk of exposure to Covid-19 infection.”
Dr Henry said the HSE was aware that Niac monitored new evidence as it emerged and would “continue to provide ongoing guidance based on the available evidence on all aspects of vaccination to ensure the vaccination programme remains safe, effective and evidence based”.