The Taoiseach said the shortfall of Covid-19 vaccines last week will be made up in the coming days.
The HSE missed its target of administering 100,000 doses of the coronavirus vaccine.
Figures published on Monday shows that 81,843 doses were administered last week, falling short of its 100,000 target.
The HSE said it was told by AstraZeneca late last week that its deliveries were being deferred.
Micheál Martin told the Dáil that the company believes the shortfall will be made up in the next week and further doses of the vaccine will be delivered.
He said there has been "bumps along the way" in the delivery of vacci
"The key is the ongoing issue of supply from AstraZeneca, Pfizer BioNTech and Moderna," he added.
"There have, without question, been bumps along the way, most recently a shortfall of supply last week from AstraZeneca, as the chair of the (vaccine) taskforce said last Saturday."
The vast majority of the over-85s will have received their coronavirus vaccine by the end of the week, the Department of Health said.
Co-leader of the Social Democrats Roisin Shortall raised concerns over the number of vaccines forecast to be delivered.
She told the Dail there is a "very substantial gap" between the numbers of vaccines to be delivered and the number that is being administered.
Ms Shortall said that vaccines provide great hope for people, and that the vast majority of people are really looking forward to getting them.
She said that people are keen to know when they're likely to receive the vaccine.
"Many of us have been looking into the Minister for Health (Stephen Donnelly) to provide the figures in relation to the performance of the vaccine programme," she added.
"I know you and the minister has said that we're delivering the vaccines, we're getting them out and administering them as quickly as they arrive, but there's no way of gauging that.
"While we're getting the daily figures for the administration of the vaccine, the other side of that equation is in relation to the number of vaccines that have arrived in this country is not available.
"The only data that is available in relation to vaccine deliveries here comes from the Path Ahead document, and there's a table set out there, so they're the only official figures we have for the forecasted deliveries.
"Those figures would indicate that there's a very substantial gap between the numbers of vaccines forecasted to be delivered here, and the number that are actually being administered - a very, very substantial gap."
She said that more than two thirds of AstraZeneca vaccines have not to have been administered, while four fifth of Moderna has not yet been administered yet.
Ms Shortall called on the Government to publish the daily figures of the numbers of doses received by the State.
"I think it's really important to have all of that data on a daily basis," she added.
Mr Martin said the issues around supply were discussed at the European Council meeting.
He said there was a dedicated meeting last Thursday about European-wide vaccination.
"China, America and Europe are the major production centres for vaccines and supply is the issue across the board," he added.
"Europe has appointed a Commissioner to deal with removing bottlenecks affecting supply.
"In the Irish context, we are administering that which we are getting in."