The largest individual shipper container transported here with the Pfizer BioNTech vaccine would be capable of delivering enough jabs for 2,437 people, it was confirmed yesterday.
The shipper - likened to a large pizza box - would contain enough to provide the full two doses to this number of people over three weeks.
However, a smaller shipper container would only provide enough doses of the vaccine for 487 people.
As the European Medicines Agency looks set to recommend approval of the vaccine early next week, it is still unclear how much will be in the first limited consignment bound for nursing home residents and frontline health workers.
Each vial in the shipper has five doses.
A spokeswoman for Pfizer said the shippers can hold a minimum quantity of 195 vials or a maximum quantity of 975 .
But each person who is vaccinated must get two doses.
Professor Brian MacCraith, who chaired the task force which drew up the plan for the roll-out of the vaccine, said it is still not confirmed how many shippers will come here initially.
It could be one shipper enough to vaccinate 2,437 people or "multiples" of that.
It is expected that hundreds of thousands of doses will be made available over the first six months of 2021.
Prof MacCraith was appearing before the Oireachtas health committee where it emerged that much work has still be to done on key elements of the plan, including on the new online registration and monitoring system and also regarding the numbers of trained doctors and nurses needed to administer the vaccine.
The priority list for the vaccine may also end up being changed, but this is dependent on levels of vaccine and other variables.
Prof MacCraith said there are around 78,000 residents in long-term care - the top priority group to first get the vaccine along with thousands of frontline healthcare workers.
It could be that the residents in around 600 long-term care homes could have been vaccinated by the middle or end of February.
However, Prof Karina Butler, chair of the immunisation advisory committee, said it may be the wrong time of the year to be "descending" on nursing homes with the vaccine.
She said "we have to recognise" the time of year and it is important to look at what is practical to do with the first limited batch of vaccines.
"It may not be reasonable to suddenly land on a nursing home in the intervening period between Christmas and the New Year," she said.
"You need to give people time to get the information and to give their informed consent."