A number of opposition TD have expressed concern about the Government's Covid-19 vaccination strategy.
Sinn Féin's health spokesperson David Cullinane said that there was a "lack of detail" around the plan and he said there were issues around staffing levels and infrastructure.
Social Democrats co-leader Róisín Shortall said she was worried about the number of vaccinators that are available to the HSE.
Their comments follow a briefing with experts involved in coordinating mass inoculations.
The briefing was attended by Professor Brian MacCraith, head of Ireland's Covid-19 Vaccine Taskforce, Professor Karina Butler, chair of the National Immunisation Advisory Committee, and Dr Colm Henry, Chief Clinical Officer with the HSE.
In a video posted to Twitter tonight, Health Minister Stephen Donnelly said the HSE would be "mobilising 65 vaccination teams, including hospital vaccinators, community vaccinators, school vaccinators and the National Ambulance Service to go into our nursing homes and protect our most vulnerable.
"They will be vaccinating seven days a week into the night."
He said a decision had been made to use some of the one-week "buffer" of the Pfizer-BioNTech vaccine.
"We had kept a buffer as it’s a two-dose vaccine and other countries have had supply chain issues. Thankfully, our supply has been constant and we’ve received solid reassurances from Pfizer on future deliveries," said Mr Donnelly.
Earlier, he told RTÉ News the roll-out of Covid-19 vaccines to nursing homes was being accelerated by one week.
He said that everyone in these settings will receive the first dose of the vaccine in the next 16 days.
Minister Donnelly said this acceleration would mean that over 70,000 people from nursing home settings and more than 70,000 healthcare workers would have received their first doses by the end of January.
The plan is to have the second doses administered to those in nursing home settings by the middle of February.
Yesterday, HSE Chief Executive Paul Reid revealed that 15,314 first doses of the vaccine have been administered from the 81,900 doses that have been delivered.
This morning, the European Commission announced that it has agreed a deal to purchase 300 million more doses of the Pfizer/BioNTech vaccine, which should mean the country will receive an additional 3.3m doses.
Mr Cullinane said that he could not get clarity at today's briefing on how many staff will be needed to administer vaccines.
He said that 15 mass vaccination centres have been promised, but as of this morning just one site has been identified.
"They still have no detail in relation to the other centres," he said.
Ms Shortall told RTÉ's Drivetime that it has not been made clear by the HSE how many vaccinators will be available to help in the delivery of the rollout.
She said "we cannot afford to have the issues that happened with the testing and tracing" and that the HSE needs to "look in all possible areas to bring staff on board to vaccinate people as a matter of urgency".
Also today, the head of the Government vaccine task force said he did not accept that the roll-out of the vaccine to date has been slow.
However, Professor MacCraith said he was cautious about giving a number on how many people will be vaccinated during the first quarter of the roll-out.
Prof MacCraith said there is a growing confidence that the "game changer" will be the arrival of the Oxford/AstraZeneca vaccine.
He reiterated that as vaccines arrive to Ireland, they will be administered to the most vulnerable first, adding that vaccines are to be delivered to 180 nursing homes next week.
'100% uptake' on vaccine in residential care - HSE
There has been a "100% uptake" of the Covid-19 vaccine in residential care settings so far, the Chief Operations Officer with the HSE has said.
Anne O'Connor said the HSE is "confined by" the number of doses of the Pfizer/BioNtech vaccine available.
Speaking on RTÉ's Today with Claire Byrne, she said that inoculating upwards of 50,000 people a week "would be a stretch" for the health service, adding that the "challenge is around certainty of supply".
She said the IT system that is being used to support the vaccination roll-out is "very tedious" and "labour intensive", but is being addressed and people should be able to book their vaccine themselves online "in the coming weeks".
Ms O'Connor said the Pfizer/BioNTech vaccine is much more restrictive than other vaccines.
She added that once other vaccines become available, they will be able to be administered by GPs and pharmacists, which will help significantly increase the number of people being vaccinated.
Additional reporting Laura Hogan, Dimitri O'Donnell