Health officials have been meeting to consider how to use the Johnson and Johnson vaccine in Ireland.
The National Immunisation Advisory Committee will recommend whether any restrictions should be put on its use due to extremely rare instances of blood clotting.
NIAC's experts are looking at a number of things.
One is the use of the single-shot Johnson and Johnson vaccine in Ireland after the European Medicines Agency advice on the issue.
The EMA said the benefits outweigh the risks when it comes to rare instances of blood clotting associated with the vaccine.
One option being considered is limiting the use of J&J to a certain age group, in a similar way to AstraZeneca.
Immunologist Professor Luke O'Neill and Professor Sam McConkey from the RCSI say it should be available for those over the age of 25 or 30.
Timing
NIAC is also set to consider the spacing out of the MRNA vaccines from Pfizer and Moderna and whether to leave more time between first and second dose in order to get more people their initial vaccination.
It's unclear when NIAC will issue its recommendation.
Yesterday government sources said there would be no decision until next week, but there is a push to speed things up today.
