The European Medicines Agency is expected to announce new advice about the use of the single-shot Covid-19 vaccine manufactured by Johnson and Johnson's subsidiary Janssen on Thursday next week.
Ireland currently has 14,000 doses of this vaccine in the HSE cold storage facility at City West in Dublin.
A further 26,000 doses are expected to be delivered to Ireland before the end of this month with a total of 605,000 doses due by the end of June.
No country in the European Union has yet administered the Janssen vaccine while all have been awaiting updated advice about its use from the European Medicines Agency.
The Agency has been considering the impact and the importance of so-called safety signals related to the use of the Janssen vaccine in the United States where cases of very rare blood clots have been observed in a very small number people who received the vaccine.
The very rare blood clots observed in the United States are similar to the Cerebral Venous Sinus Thrombosis clotting events involving low blood platelets that the European Medicines Agency recently said were linked to the Astra Zeneca Vaccine.
The same scientific technology is used to make both the Janssen and the Astra Zeneca vaccines.
In making its advice next week the European Medicines Agency will be relying on international data regarding the safety of the Janssen vaccine including analysis from the US Food and Drug Administration and the US Centre for Disease Prevention and Control because there is no European data available yet about very rare side effects of the vaccine.
Following the publication of the EMA's updated advice next Thursday Ireland's National Immunisation Advisory Committee (NIAC) will have to meet to consider its implications before issuing its own advice.
There is speculation that NIAC may recommend some form of age limits for the use of the Janssen vaccine. If that happens it could have an impact on Ireland's vaccine rollout plan.
However, all that remains to be seen and it will depend on what the EMA reports next Thursday.